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Paul DeLong

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Paul is the “the best part of training,” according to PLAYBOOK's clients. Paul hones his lean and agile skills mountain biking where no man has gone before!

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Lean Project Management (part 8): Using shared team buffers just makes sense

Paul DeLong- 03/30/17 12:15 PM

What is a shared project buffer?  

To accommodate for the uncertainty in the work estimates and the resource’s availability to do the work, the artificial, invisible task buffers are replaced with a shared team buffer at the end. The published completion date (promise date) is at the end of the shared team buffer.

How do we estimate the size of the shared project buffer?

Instead of artificially buffering all our tasks, we estimate durations using a 50/50 guideline - 50% of the time the task will be completed on or before the estimated date and 50% of the time the task will take longer. These are sometimes referred to as focused durations.

We then focus (single-task) on the task until it is complete. We’ll do the same amount of work, have some margin, work under less stress and we’ll likely complete the project sooner.

Read our complete guide to Lean Agile project management here.

View the Guide

What's the benefit of using a shared project buffer?

The length or size of the shared team buffer is smaller than the sum of the task buffers, because we benefit from variability pooling, similar to statistical tolerance analysis. If you’d like to learn more about how to size buffers, click here.

Why don't individual task buffers work?

Let's look at the rationale behind why individual task buffers don't work.

Student syndrome

To explain individual task buffers, we’ll start with a discussion about Student Syndrome.

Student Syndrome refers to people’s tendency to procrastinate - only starting to focus one’s effort on an assignment at the last possible moment before its due date.

 

Picture1

 

What happens is that we multitask, unknowingly causing more delay, until a task’s due date approaches, which invokes a sense of urgency followed by a more concentrated effort to complete the task.

Picture2

Sometimes the task is completed by its due date and sometimes it takes longer.

 

Picture3

 

Student Syndrome consumes potential safety margins, puts people under stress and pressure, and often requires heroics to get the task done. The impacts of Student Syndrome is that each and every task takes longer, causing the project to take longer, and the resource may cut corners because they’re late.

Parkinson's Law

But that’s not all. There’s another phenomena affecting how long it takes us to get the work done – Parkinson’s Law. Parkinson’s Law is the adage that the “work expands to fill the time allotted.”

For example, the larger the suitcase we bring on a trip, the more stuff we pack, right?

 

Suitcase

 

So, the more time we have to work on a task, the longer we work on it, forever trying to improve or perfect it.

“Perfect is the enemy of good enough.”
-Voltaire

The prevailing culture that feeds into Student Syndrome is one in which task duration estimates are treated as commitments and being late is unacceptable, therefore it’s better to under-commit and over-deliver.

For example, if Mary, Bob and John think their tasks will take them 5 days each to complete, they might commit to have each complete in 10 days, for a total of 30 days. This is a safe bet. Mary and Bob have high confidence they’ll complete the tasks no later than the commit date. Estimates like these are referred to as 90/10 estimates, 90% confidence the task will be done by the estimated completion date and a 10% chance it won’t be.

 

Picture4

 

Since we’ve been measured on our ability to hit due dates and being late is unacceptable, we’ve been conditioned to pad our estimates (90/10 estimates). This padding is what we refer to as individual task buffers.

In fact, because of Student Syndrome and Parkinson’s Law, the individual task buffers typically get used and often the time to complete the task extends beyond the buffer.

The bottom line impact of Student Syndrome and Parkinson’s Law is every task takes longer causing projects to take longer.

"Insanity == Doing the same thing over and over again expecting different results."
- Albert Einstein

Nothing will change unless we do something differently. If we could adopt a new way of executing our work, we could get projects done sooner.

Using shared team buffers just makes sense

Instead of artificially buffering all our tasks, we estimate durations using a 50/50 guideline - 50% of the time the task will be completed on or before the estimated date and 50% of the time the task will take longer. These are sometimes referred to as focused durations.

We then focus (single-task) on the task until it is complete. We’ll do the same amount of work, have some margin, work under less stress and we’ll likely complete the project sooner.

 

Picture5

 

For example, if Mary, Bob and John think their tasks will take them 5 days each to complete, then their 50/50 estimates for each task is 5 days.

 

Picture6

 

To accommodate for the uncertainty in the work estimates and the resource’s availability to do the work, the artificial, invisible task buffers are replaced with a shared team buffer at the end. The published completion date (promise date) is at the end of the shared team buffer.

 

Picture7

 

The length or size of the shared team buffer is smaller than the sum of the task buffers, because we benefit from variability pooling, similar to statistical tolerance analysis. If you’d like to learn more about how to size buffers, click here.

Because we’re single-tasking more and multitasking less, fewer tasks will go to full buffered length and some will get done early.

If we adopt this new way of executing our work, we will complete projects earlier and with greater confidence than the traditional individual task buffered approach.

Key Principle

Using visible, shared team buffers, instead of artificially inflating schedules by buffering every task, drives focus and encourages teamwork.

How do you monitor shared buffer consumption?

The shared team buffer is like a cake (yum, did someone say cake?!).

 

cake

 

Those involved in earlier phases of the project aren’t allowed to eat all of the cake, only their portion. They have to leave some cake for the downstream activities, such as verification testing, manufacturing, etc.

Buffer Charts (fever charts) are used to track the performance of the project by tracking the amount of buffer consumed, visibly.

 

Picture8

 

Typically buffer usage is charted weekly. If this week’s usage is in the green, the project is on track. If it’s in the yellow, the project is starting to use the buffer too fast and the team plans interventions. If it’s in the red, the team executes interventions. If you’d like to learn more about Buffer Charts for Power Users, click here.

In PLAYBOOK buffers are made visible using a task.

The amount of buffer used is seen by looking at how far the Project Complete milestone has moved across it. When the Project Complete milestone reaches the end of the buffer task, all of the buffer has been used.

 

Picture7

 

You may be thinking, “What? If I remove my teams’ commitments to Due Dates – won’t the tasks take even longer?!”

There is a common concern among managers that removing commitments to due dates on tasks will cause engineers, for example, to keep working on their design much longer than they would with a due date. This concern is certainly valid, but there are good ways to prevent people from ‘over-polishing the BB’ without resorting to task commitments (and therefore individual task buffers). The answer is three-fold:

1. Visibility to the resource’s work

2. A little peer pressure (via shared team buffers and standup meeting).

3. A good Definition of Done for those tasks where the end is not already clear

We’ve discussed the virtues of visibility to the work in several posts in the series. It is a key ingredient in successfully accelerating projects. In the next post we will discuss standup meetings for fast feedback. Stay tuned…

 

Ready to learn more?  Watch a demonstration video of PLAYBOOK's Lean and Agile project management software.

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This is the eighth part in our series on Lean Project Management (LPM) and Visual Work Management (VWM) for hardware development teams.

In this part we discuss another way to reduce multitasking and the next Lean project management principle: replacing individual task buffers with 

The series is broken into 10 parts that cover the following topics.