"If it ain't broke, don't fix it".
Sometimes if you have something good, it's best to just work with that rather than bring something else in with flaws. It usually ends up being a waste of time and labor.
Much as we'd all like to have perfection, in chickens, dogs, horses, cattle, or any other domestic animal, even tropical fish, there's always a weak link in the chain that's eventually going to manifest itself.