The good is the enemy of the best
(the) good is the enemy of (the) best
Settling for things that are merely good or adequate can prohibit one from achieving that which is ideal. My opponent wants our government to provide only enough funding for "good" services—good schools, good hospitals, good infrastructure, and so on. But good is the enemy of the best, and that is why he and his party will never lead our country to its fullest potential. You should never allow your employees to get away with mediocrity, for the good is the enemy of the best, and if left unchecked it will hinder your company's ability to grow.
The good is the enemy of the best.
Prov. Instead of making things the best that they can, people often settle for making them merely good. Mother: Aren't you going to rewrite your paper? Child: Why? It's good enough. Mother: The good is the enemy of the best.