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“Magic Trick”: How to Increase Activity Duration and Reduce Project Duration?

Meet the author:

Tal Levanon – Founder and partner in “Tal Levanon – HCP Ltd”, an expert project scheduling consultant and creator of the Hidden Critical Paths (HCP).


Once, I learned a magic trick – how to increase task duration in a project, on the critical path, thereby reducing the overall project duration!

At the very least, this sounds strange, doesn’t it? How can it be?

Two important notes:

  1. Because it’s magic, the estimates of required activity durations don’t necessarily have to be grounded in reality. This is only to explain the magic😊!
  2. Magic is all about deception – something that looks like something else but really isn’t. This is not what we’re doing here. This magic trick is absolutely practical in reality!

Let’s look at a small project: constructing a 3-story building.
We’ll simplify the construction as: “construction walls and ceiling for story X”, “plaster for story X” and “paint for story X”.

For presentation purposes only, we’ll assume a standard 5-day work week (unrelated to the 
trick 😊).

HCP app | “Magic Trick”: How to Increase Activity Duration and Reduce Project Duration?

Project management: stage 1 – constructing the stories

Let’s assume that it would take 5 workdays to construct a story’s walls and ceiling. This is magic, remember?

Obviously, story #2 cannot be constructed before finishing story #1, and surely story #3 cannot be constructed before #2.

(The clever ones among us would then say – the building can be divided into two parts – or more, and we will construct them gradually. Then, story #2 can be constructed before finishing story #1. You’re right! But bear with me for a moment – because, again, this is not what the trick is about 😊)

This is how the wall and ceiling construction stage will appear in Project, Primavera or in any other software:

HCP app | “Magic Trick”: How to Increase Activity Duration and Reduce Project Duration?

Each story will be constructed once the lower story was finished, meaning, the activities will be linked by a finish-start procedure.

The result: constructing walls and ceilings would take 15 days – 3 weeks. If construction begins on Nov. 4th, it will end on Nov. 22nd.

Project management: stage 2 - plaster

Now we need to apply plaster to the walls. Plastering requires 3 days on each story. However, not all walls in a single story must be finished before we can begin plastering the same story. The important link is that once we finish constructing the last wall on the story – we would only need two more workdays on that story. Meaning, the link between finishing the construction on the story and finishing the plastering job will have a finish-finish + 2 workdays link. It would look like this:

HCP app | “Magic Trick”: How to Increase Activity Duration and Reduce Project Duration?

The result: plastering ends on Nov. 26th, two workdays after finishing the walls and ceiling of the 3rd floor.

Project management: stage 3 – painting walls

We can now paint the walls. To paint the walls, each story requires 4 workdays. Painting can be done concurrently with plastering: you can start painting walls after two days of plastering. Meaning, wall plastering and wall painting have a start-start + two workdays connection. It would look like this:

Schedule management, schedule evaluation, Gantt Chart Project Management, Gantt Chart, Gantt Project Management, Schedule, Schedule management, Schedule manager, Schedule project, Schedule manage

The result: the building’s painting job ends on Nov. 29th, and with it – the whole project!

Project management: stage 4 – a meeting to update the PM and contractors + magic trick!

The project manager, who worked hard on building the schedule, meets with the plasterer and painter to guide them about the project. “No way!” yells the painter. “I’m not willing to work – go someplace else – come – and go. No way! Either I work at least 4 days a week or I come at the end and do the whole job in one go!”

A moment before the project manager starts shouting at the plasterer, he makes a schedule adjustment: he sets the plaster job as requiring 4 days per story.

HCP app | “Magic Trick”: How to Increase Activity Duration and Reduce Project Duration?

The result: the entire project ends on Nov. 28th. One day earlier!

Magic, right? 😊

One request – if you use this trick – share your experience in the comments. It’s the best!

You received a schedule (Gantt chart)
with hundreds of activities.
Do you want to know what happens inside,
and if there are problems, where are they?

If you answered 'YES' - then we have a solution for you!

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