Which Constraint Helps a Creative Project Reach the Finish Line?

A project can keep collecting tiny improvements long after its main idea is clear. Sometimes the useful next step isn’t another possibility, but a boundary that makes “finished enough” easier to recognize.

What kind of constraint helps you complete creative work without flattening what makes it yours—a time limit, a cap on revisions, or a clear audience need? What would tell you it’s time to share the draft?