Why a project plan?

While it is true that deviations from the plan will occur in nearly all projects, the project plan is a reference point that aims to inform you about where you are and where you should go next.

The project plan is a reference point used to navigate projects, i.e. point out where you are and where you want to go. The plan is to be adjusted continuously, making necessary changes considering unexpected events that will nearly always happen.

Dwight D. Eisenhower once has said

“In preparing for a battle, I have always found that plans are useless but planning is indispensable”

Hence, to be able to plan (planning) you need a plan.