Long ago when I was working on my degree, I observed that it took a measure of OCD (obsessive compulsive disorder) to complete advanced work. You have to work hard, work consistently, and really care about the outcome.
But there were people for whom NOTHING was ever good enough: those who could not hand in a paper without agonizing, who were never satisfied with any of their work, and who, in the end, could not complete their final thesis for fear that it wasn't perfect.
There is such a thing as too critical about accuracy - and I would say that if it keeps you from completing things, if you are harsh about your work in a way that you would never be harsh about others' - you might want to reassess. Perfection is impossible.
As as bearisgray pointed out, often "good enough is good enough."