How many times have you produced a perfect piece? For me, it's rare because I am always seeing ways that things could have been done better.
The fit might have been a bit tighter. The finish could have been better. The wood should have been more carefully chosen. The project budget might have been too tight to allow for the extra time but maybe I could have negotiated a better price.
The small things loom large for makers. Sometimes, that "one little thing" ends up being the only thing you can see in a finished project regardless of how fine it might be overall.
I have found that, in the long run, it is better not to let these "little things" slip by in the first place.