at the beginning of my career I read somewhere if it ain't broke don't fix it. If that is making money and you can black box it, then do not fix it, for sure yo

at the beginning of my career I read somewhere if it ain't broke don't fix it. If that is making money and you can black box it, then do not fix it, for sure you could always add some test around the black box and then move on. Try to create new software outside of that box that reflects the same ideals that you would have put into "refactoring" the "bad one".