The Planning Fallacy

Optimism is useful. A realistic schedule also makes room for the work that rarely goes to plan.

You know that project you were certain would take one week?

Three weeks later, you are still saying, “We’re almost done.”

We tend to plan around the version of the project where everything goes right. No interruptions. No delayed approvals. No missing information. No unexpected problems.

Unfortunately, that version of the project rarely exists.

This is called the Planning Fallacy:

We usually underestimate how long a task will take.

It is not always poor planning. Sometimes it is excessive optimism disguised as a schedule.

A better estimate usually comes from asking how long similar work actually took before, not how quickly we hope this one will go.

Hope is useful.

It is just not a calendar.