perfect is the enemy of (the) good

To allow the demand, desire, or insistence for perfection to decrease the chances of obtaining a good or favorable result in the end. (Usually used as an imperative in negative constructions.) I know you want your research paper to be great, but remember that perfect is the enemy of good. I mean, you'll fail if you don't even finish it in time! As a manager, you have to realize both the potential and the limits of your employees. Keep in mind that perfect is the enemy of the good.