A clear ending makes the effort available to someone beyond its maker.

Work that never quite finishes stays private. While pieces remain loose, only the person who made it can hold the whole shape in mind, and everyone else needs a guided tour to get anywhere. An ending is not only closure for you. It is the moment the thing becomes usable by somebody who was not there.

Take something that has been nearly done for months and define what finished would mean in one sentence. Do only that, then hand it over rather than improving it further.