How is the estimation effect of the project phases?

Accurate time estimation is a crucial skill in project management. Without it, you won't know how long your project will take, and you won't be able to get commitment from the people who need to sign it off.

Even more importantly for your career, sponsors often judge whether a project has succeeded or failed depending on whether it has been delivered on time and on budget. To have a chance of being successful as a project manager, you need to be able to negotiate sensible budgets and achievable deadlines.