The last detail matters when it decides whether the result can be trusted in ordinary use.

Not every finishing touch is equal. Some are polish, and some are the difference between a thing that works when a tired person picks it up and a thing that fails the first time anyone uses it casually. The detail worth the extra hour is the one carrying whether the result can be relied on.

Before calling something done, sort what remains into two piles: items that would cause a real problem in normal use, and items that are only tidiness. Finish the first pile and let the second wait.