---
title: "Time management"
description: "How to optimize your time & work?"
authors: ["glegoux"]
time_reading_minutes: 10
category: "Methodology"
---

You could need to **optimize the spending of your time** for **professional or personal activities**. 
I am going to explain what means for me the time, and how you can manage it. I have been inspired by my
knowledge, experiences, readings, and listenings, but it is my personal version of the time management 
between math, physics, management, philosophy, and operational research. Without giving a lot of details, 
the time management is also linked to the **agile methodologies** that is one implementation, 
like **Scrum**, **Kanban** or **Pomodoro**. 

The **time management** is the science of the usage of time, a possible definition could be the process of planning and 
exercising conscious control of time spent on specific activities, especially **to increase effectiveness, efficiency, 
and productivity**.

{% include article-google-drawing.html title="Time Management"
src="https://docs.google.com/drawings/d/e/2PACX-1vR9gDDDWTNK3btntBfhxsrL18EDGgytkOLDCS2yrgp8ZqxgvJQsCpnyWJwWT4cIk_8z0rLUn1iTS8cG/pub?w=600&h=348"
%}

The way whose you can **use your time** depends on a lot of things, among others there are your:

* **context**:
    * which resources you have (knowledge, time, energy, money ...)
    * what are your features (skills, experiences, character traits ...)
    * what are your constraints (costs, exigencies, ...)
* **projection**:
    * what you want to do (ambitions, preferences, choices ...)
    * what are your goals (objectives, key results, tasks, sub-tasks, projects, missions ...)
* **strategy**:
    * how you organize your activities (priorities, hierarchies, dependencies, sizing, partitioning
      ...)
* **analysis**:
    * how you know yourself (strong points, weak points, personal will and effort ...)
    * how you have a projection & strategy coherent of yourself (clairvoyance, honesty, realism ...)
    * how you receive a critical opinion positive or negative on yourself (feedbacks,
      auto-introspections, questionings, doubts...)

# How to define the time?

With the meta-physique considerations, the **time** has wondering features: **universal, continuous, unlimited, 
non-renewable, solid (incompressible/no expansible), perpetually self-generated, no accumulative**. Focus us on the **timescale** of our **human life**.
These features are immutable, or more precisely their changes are negligible. But we can interpret the time differently.

Here I am going to interpret the time like a **quantizable object** with an arbitrary windows in the **past, present or future**.
The present moment is seen like a progressive cursor representing a dynamic **instant** on the **timeline**. This present instant 
plays the role of irreversible transformer altering the future into past. The **duration** of an **event** is the length of a **windows time** 
delimited by 2 instants where the event began and finished. For the following, when I speak about time, I refer to this **sliding windows**.

{% include article-google-drawing.html title="Time vs Duration"
src="https://docs.google.com/drawings/d/e/2PACX-1vQMPHMxeI8O86epOjBylFK4Pv1L71MKeIki-rfSJzG5wZ9jeickJi_y32JDWLGqLlXqm0lTj-3vBBge/pub?w=537&h=147"
%}

<div class="info">
The <b>time</b> :clock2: is one of our <b>most valuable resources</b>, for me more important than the
knowledge, the money or the energy, because all ones depend on time.
</div>

It is important to distinguish the **absolute time**, and the **subjective time**. The quantity of
elapsed time to carry out an activity can be **viewed and interpreted subjectively**. The same
quantity of time measured objectively in **seconds** could be lived differently by 2 different
people esteemed like **short or long**. Take into account this subjectivity, because the time
management is more relevant if it is applied individually with your sensibility.

For example, **a sharp mind** on a particular situation will have the feeling to life in accelerated
time by interacting with a less sharp mind, because he compares his thinking speed to that of his
interlocutor, and this one is faster, and reciprocally. Another example is when you are doing a
**passionate activity**. The time seems to go faster, because you forget the feeling of elapsed
time, and inversely with the boredom.

The absolute time allows to compare the duration between 2 activities objectively, but when you want
to organize or optimize your time, you need to adjust your efforts with your personal consideration
of an elapsed time for a given activity. The **elapsed time** can be interpreted as a **sum of done
activities**. The **unit measure of an activity** is subjective, and could be called **weight**,
where are mixed the **quantities of used resources** to do the activity (for example the quantities
of time, energy or money). Here more the activity has a light color, more the activity has a light
weight:

{% include article-google-drawing.html title="Time usage"
src="https://docs.google.com/drawings/d/e/2PACX-1vR_VEmMKNndJR493-_obuNMiuI0c3h_MeUADJoeCJF7KdAPEuAgJm0F-f7U_UF4bF-aStk1pQZF5A6K/pub?w=537&h=147"
%}

The time could be considered as a quantity of spent resources during a duration (itself in another meaning)
to do activities now. So the **quantity of available time at your disposition** 
does not respect the time features mentioned previously, it is:

* **personal**: you have a personal context and subjective time
* **discrete**: you have a minimum time of reactivity your frequency sample to measure the elapsed time
* **limited**: you have a life length and resources which are finite
* **renewable**: you can renew some activities in the future
* **compressible/expansible**: you feel of elapsed time differently for a given activity in function
  of time
* **occasionally generated by you**: you make your choices, and your organization to free of time
* **cumulative**: we interpret the time with a quantity now, no only an instant

But the quantity of time is always available immediately.

# The concepts of the time management

We defined several ways to conceptualize the time, here I can define more precisely the other
concepts of time management like the **effort** and the **optimization**.

The **effort** to do an activity is like the **way of consummation of a quantity of resources**.
Your resources are renewed perpetually and has a **potential**, the activity has also a **potential**.
You need to create a resources flow, called the **intensity** of the effort, to do the activity.
The awareness to practice an extreme effort in quantity (too much or too few) or quality (too easy or
to difficult) slows down the feeling of elapsed time, and extends the time. This reduces your
endurance on this activity. But the practice and the training allow you to reduce the feeling of
effort, you consume less and/or have more of resources.

It is important to observe that the optimization of the **time usage** is in fact the optimization
of future projection of the productivity of an activity on a time range. This
**optimization** is **under constraints** and depends on **objectives**, called also goals. To
achieve these goals one of the **available resources** to use and save is the time.

I use several concepts above without defining them, here a summary:

* **Goal**: definition of result(s) that you want to get, called also objective.
* **Task**: definition of action(s) that you want to mean to achieve at least one goal.
* **Activity**: execution at least one task over time.
* **Productivity**: measure of your performance that is a combination of effectiveness and
  efficiency.

# A model of optimisation

The **time management** can be seen the **modeling of an objective function**
to optimize. The model of this objective function is fixed by the **definition** of your **goals**
(split into **tasks**) and of the **execution plan**. Then its optimization is determined by the
duality between the **minimization** of the **cost of executions** and the **maximization** of 
**quality of got results** for a set of tasks.

In mathematics terms, that is to say optimize the **objective function** $g \circ f$ on a set of tasks $\bigcup x \subset X$
where:

$$f: X \rightarrow \mathbb{R}^+ \times \mathbb{R}^+ \quad x \mapsto f(x) = (c(x), q(x))$$

$$g: Img(f) = \{\,f(x)\,|\,x \in X \} \subset \mathbb{R}^+ \times \mathbb{R}^+ \rightarrow
\mathbb{R}^+ \quad y \mapsto g(y) = g(f(x)) = g(c(x), q(x))$$

* $c$ is the **cost function** of executions
* $q$ is the **quality function** of got results
* $f$ is the **productivity function** in terms of efficiency and effectiveness
* $g$ is a **trade-off function** between the minimization of the cost $c$ and maximization of the quality
  $q$ on subset of $X$

{% include article-google-drawing.html title="Objective function is a trade-off: cost vs quality of
a set of tasks"
src="https://docs.google.com/drawings/d/e/2PACX-1vQWBneRL7immMkY2pHZ1FMm7Kz3LNDcrF7by2pUAonxbNXIBP9dKNtc0NohlMi72y8Duk1BJaTZCwWg/pub?w=500&h=366"
%}

<div class="warning">
But the stability, the evolution of the objective function depends on your <b>regularity</b>, your <b>implication</b> and your <b>progress</b>.
</div>

The functions $c$ and $q$ are often linked, and it influences generally each one negatively for the
optimization: reducing the cost reduces the quality, and increasing the quality increases the cost.
While our optimization consists in reducing the cost, be **efficient**, and in increasing the quality,
be **effective**. It is often more performant to be firstly effective, then efficient for a given
task. Learning to do correctly a task before doing it faster. But it is clear, that be
effective and efficient (at the same time and in good proportion) is the final goal for each task.

<div class="info">
You can do an analogy with the <b>machine learning</b> algorithm. The execution plan is your <b>model</b> owning <b>hyper-parameters</b>, 
the tasks are rows of your <b>dataset</b> (training, validation, test) and the maximization of the objection function is the step of <b>learning</b>. 
With experience on an execution plan, you can predict the speed of execution and the quality of results.
</div>

# A methodology of usage

After having modelled and defined the concepts of the time management, I am interested here by
applying it in practice through a methodology. Firstly, even if you can model the time management,
in my point of view it is an **empirical science**. That is to say, you need a methodology to test
it, and your knowledge about this science will be provided by your experiences and your
observations.

<div class="info">
Here the <b>main considered resource</b> is <b>the time</b>, but in practice the methodology could be more complex you could consider 
other inter-dependent resources to spend like the money or the energy.
</div>

## Define your personal context

You need to list and put into perspective your resources, your skills, and your constraints.

## Define your projection

After you need to define what you want to do, and build your **goals** each one with a **dateline**.
Do a first pass of the following section strategy applied to your goals (replace activities with
goals). Once your goals are partitioned, hierarchized, sized, prioritize, sequenced. Your destructed
goals should now fill in a **coherent structure**. Then split each goal in tasks. You can repeat
this operation to split each tasks into smaller activities to pass **from a macro timescale to a
micro timescale**.

## Define your strategy

The strategies are the fact to structure your activities to reach out.

* **Partition your activities**

Partition your activities which has same **type** in **independent class** between them the more
possible. Of course, the content of each **partition**
is subjective for some activities, you can classify your activities into these partitions
differently in function of your sensitivities and interests. You can already give an important
weight to each partition.

{% include article-google-drawing.html title="Partitioning"
src="https://docs.google.com/drawings/d/e/2PACX-1vRt1dc1fZp69-BO05hjcdjSoRflDhlTG_9NmctQRn-EbmvITD_Lg2xlgT-MqsnkAF7XA_31X0Uv-a0m/pub?w=300&h=321"
%}

* **Organize into a hierarchy your activities**

Here the goal is to estimate roughly the weight of an activity to have its order of magnitude.

Each goal should be realist, reachable, measurable with success keys, and sized in difficulty and
required time to achieve it. You can play on **several scales** for your future projections:
**very long term, long term, middle term, short term, and very short term**.

{% include article-google-drawing.html title="Scaling"
src="https://docs.google.com/drawings/d/e/2PACX-1vT2INReaOVrCjN2rKrOCBToYqXnIg6dU7hHGiwSvcZl_7Lg6uXqoj5aNlV68abuP29q_OaZm6vc5bPF/pub?w=480&h=360"
%}

* **Size your activities**

Now you can size more precisely each task. You can measure absolutely, if it is complicated, you can
also measure relatively the ones in relation to the other ones. You need to choose the unit of the *
weight* of your activity.

{% include article-google-drawing.html title="Sizing"
src="https://docs.google.com/drawings/d/e/2PACX-1vTKLnvm7RpJb3SSmZ4mEmLFyvb84e9ndFV1ehYUDe7OV5ev-yWVztyG8VE0gYpyi_KpQNyhZtuN_ToH/pub?w=200&h=331"
%}

* **Organize the interactions of activities**

You need to build a **dependency graph** of each activity to see if an activity depends on other
one(s).

{% include article-google-drawing.html title="Dependency graph"
src="https://docs.google.com/drawings/d/e/2PACX-1vSudssT0neN76LmXVxtcbVBVQEI_cVhyS6wqCWo9jqCTX2EqIJeb6qMtUvm-7XR0m2J_AWm1Ynps9qB/pub?w=250&h=289"
%}

Your **dependency graph** must be a set of **acyclic graphs**.

* **Prioritize your activities**

After you need **to rank your activities** which ones are the most important ones:

{% include article-google-drawing.html title="Prioritizing"
src="https://docs.google.com/drawings/d/e/2PACX-1vS8OzDo_ArOse_qIVYYg1yati0qf8MeIyxeiP_bL618xEMEFxdBwLGiFK1jsj66hY7OPzCz-rlP71Kl/pub?w=245&h=240"
%}

* **Sequence your activities**

It is you build your **plan of execution** by sequencing each activity by respecting the previous
steps and your other constraints:

{% include article-google-drawing.html title="Sequencing"
src="https://docs.google.com/drawings/d/e/2PACX-1vTaWiI1eOkX3AKOSixZzaKHyXRaMc7_RVdFqwglYzHhfMss0hQ7No16GBqfDbzJqM1hfNk1Pw7wDdpV/pub?w=573&h=145"
%}

You can also optimize these sequencing.

## Have an auto-analysis

Now you can execute your plan. But you need to **monitor** it, and have logs, metrics and traces,
and have dashboards to visualize it. You need to do regularly **retrospectives** and **plannings**.
Respectively to adjust your strategy in function of time, and continue to converge to the filling of
your goals. Then to define new goals or delete goals in order to avoid the shortage of tasks, the
overload, or the accumulation of deprecated goals. Then you need to measure with your **KPI** your
productivity. You need to have a **feedback loop** to build your **virtuous circle**, and iterate on
it.

# For example for your lifetime

Are you a student, a worker or a retiree? Take the example of a worker, more precisely a professional
software engineer full-time working exclusively for a unique company at the beginning of its
career. By hoping, that it matches to your **auto-introspection**, else the following could help you to do
the same thing for your personal context. I give you here only a **partial overview** of how it can be done, 
this example is not necessary my real usage of my personal time.

{% include article-google-drawing.html title="Timescale of the human life"
src="https://docs.google.com/drawings/d/e/2PACX-1vTP167tBMm4i3nTOrf72NzpkGNLuTAVMnsQqdasktHiuAnOx-AMG1G9We3qWRADeDgrfCC3EV2Oxwm7/pub?w=537&h=147"
%}

I analyze my resources, my constraints, and my features (hard skills and soft skills, ...).

Above all, I define what I want to do and my ambitions: following conferences, coding an open-source project, having a side project, 
becoming a speaker, losing weight, finishing TV series, reading books, following trainings, giving courses ...
Each goal should be precise, measurable and reachable. 

I split my activities into 3 partitions:

1. **Life activities**: required vital, society or community activities  
   *for example: sleep, eat, wash, practice a physical activity, interact with your environment, do
   the housework, pay the taxes, see your friends ...*
2. **Work activities**: required activities for your job  
   *for example: commute, work, do a brainstorm, code, participate in a meeting, take break ...*
3. **Personal activities**: spare and free activities  
   *for example: practice its development personal, relaxation ...*

I focus me on the **life activities** that composes my lifetime. I let on the side the work and personal activities, it is the principle. 

For example, for the different timescales, I take long: ~hour and short: ~minute. 
I try to evaluate the time of each life activity:

* sleeping: 7 hours per day
* washing yourself: 2 times 3 minutes per day for teeth and 15min per day for body
* eating: 2 times 20 minutes per day for lunch and dinner with 10 minutes per day for the breakfast
* seeing friends: at least one time per week for several hours
* practicing sport: 3 hours per week
* doing the other tasks: several hours per week (taking out the trash, preparing the meals, doing housework, shopping, do-it-yourself ...)

These activities are not really dependent, and with the same priority for me. Now I sequence them for each period of a day and of a week.

I have a **calendar** where I can monitor each timescale and put my tasks, a **weekly planning**
for my datelines, and a **to-do list** for daily tasks.

Now I redo the same things for my personal activities, and my work activities to finish the management of my time.

# Go Further

This article is only an introduction of time management applied to oneself by onself. But the situation can
be **more complex**. For example, if you think the time management for other people, if you are:

* **Tech lead** for a team composed of a group of people
* **Manager** for a departement composed of a group of teams
* **CTO** for a R&D pole composed of departments
* **CEO** for a company or a group of companies ...

It requires delegating tasks, understanding the personal context of other people, and driving
the time management for a group of people at **different scales**. These organizations can have
different structures and different stakes. For it, you must re-define the **time management** to
resolve your new needs for **yourself** and for **another people**.

# References

* MALABOU, Catherine. **Le Temps**. Hatier, 2019. 80 pages. ISBN: 2-218-71678-X.
* Saint-Augustin. **Les Confessions**. 4 BC. Book XI.
* KLEIN, Etienne. **Les tactiques de Chronos**. Flammarion, 2009. 224 pages. ISBN: 978-2-0812-2305-9.
* HAWKING, Stephen. **A Brief History of Time**. Bantam Book, 2011. Chapter 2: Space and Time. 23 pages. ISBN: 978-0-857-50100-4.
* VANDENBERGHE, Lieven. **Convex Optimization**. Cambridge University Press, 2009. Chapter 1: 16 pages. ISBN: 978-0-521-83378-3.
* WINSTON, Wayne L.. **Operations Research**. Thomson Brooks/Cole, 2004. Chapter 1: 12 pages. ISBN: 0-534-38058-1.
* MURPHY, Kevin P.. **Machine Learning: A probabilistic Perspective**. The MIT Press, 2012. Chapter 1: 24 pages. ISBN: 978-0-262-01802-9.
* SUTHERLAND, Jeff. **SCRUM**. Business Books, 2014. 248 pages. ISBN: 978-1-847-94108-4.
* ANDERSON, David J. **Kanban: Successful Evolutionary ...** Blue Hole Press, 2010. 278 pages. ISBN: 978-0-9845214-1-8.
* CIRILLO, Francesco. **The Pomodoro Technique**. 2018. 160 pages. ISBN: 1524760706.
* OHNO, Taiichi. **Toyota Production System**. Synermage, 2020. 150 pages. ISBN: 106992329X.
* New York University. **Time Management**. NYC, April 2021. [Link](https://www.nyu.edu/students/academic-services/undergraduate-advisement/academic-resource-center/tutoring-and-learning/academic-skills-workshops/time-management.html)
* KOLMAR, Chris. **Efficiency vs Effectiveness**. Zippia, April 2021. [Link](https://www.zippia.com/advice/efficiency-vs-effectiveness/)