I think it was Voltaire who said that perfection is the enemy of the good. His words can be at first a kind of head scratcher. But putting his words into a Buddhist context maybe like, conduct is the enemy of the good, works better.
We can imagine this conduct to be like virtue signaling or a standard of proper behavior. It’s about trying to appear perfect in conduct as if conduct and the good are one and the same. We can even imagine zazen to be perfect enlightenment.
But conduct, no matter how perfect, is not the same as seeing our true nature or the good. Maybe we can think of the problem another way when we look at sports in the example of diving. Even with a perfect score in which all the judges agree that the dive was perfect this has nothing to do with enlightenment or the good.
Even a Buddhist monk or nun of long-standing who has never had any problem with obeying the regula of the order does not translate into enlightenment. In all religious communities there is that species of human being called holier than thou. These are people who are pretending moral superiority.
In the religion of Buddhism nirvana counts most (realizing the unconditioned). And on the path to nirvana, Zen or intuition counts most. It’s not conduct or perfect conduct or even perfect moral behavior that gets us to the other shore of nirvana.
I will say that good conduct is necessary to lead a happy interpersonal life. But when we turn to look within at our self it doesn’t work so well. All of our weaknesses and strengths lie within us as does enlightenment and our ignorance of it.