Successful projects take out uncertainty early and have enough runway to answer additional challenges or even start implementing during the project timeline. One important concept is frontloading, basically starting and completing all the tasks which you can already today.
Rarely things are all sequential and therefore starting things early, parallelizing them or coming up with work products early on are giving you critical runway later on. This is also a great capability in foreseeing how a project will turn out and how it can become even more successful.
The most successful projects in my view were completed in half the time and answered additional strategic challenges on top. If projects are running over time or answered unconvincingly very often the root cause is the project leadership or the scope from the start.
Make sure to you and your team apply this concept early on. Work hypothesis driven and finish early and successful.