Decisiveness means knowing which uncertainty deserves tolerance.

Some uncertainty is worth reducing and some is permanent, and confusing the two is what keeps people stuck. Skill here is largely about triage: knowing which unknowns will yield to more work and which you simply have to carry while acting anyway. Not everything unresolved is a problem to solve.

Split your open questions into ones you could answer with effort and ones you cannot answer at all. Work on the first group and consciously accept the second. Tolerating the right uncertainty is what lets you move without being careless.