The missing piece can make people doubt work that is already correct.

An obvious gap casts doubt backwards over everything around it. A jigsaw with one hole, a report with a blank column, a room with a bare patch on the wall: the eye lands there and the rest, which is finished and sound, begins to feel provisional. Completion does a lot of quiet persuasive work quite separately from quality. That is worth knowing before you decide something is not good enough.

If a project is being judged harshly, check whether the trouble is the missing corner rather than the whole. Fill the obvious gap first, even roughly, and watch how the judgement changes.