Though it may defy logic, the easiest way to screw up a project is to give it too much time—enough time for people to rethink, revise, have second thoughts, invite others into the project, get more opinions, conduct tests, etc.
Time allocation is critical. Too little time and we’d compromise on quality. Too much time and we’d invite overthinking. Work with smart people, and everything, including your project timelines will become simpler and more achievable.