1. Is this code in production already making profit?
2. How often is this code updated?
3. Is it profitable to fix that code or just to learn from that experience and move on?
If someone is still confused after reading these, ask yourself:
Will the profit I gain from leaving this alone allow me to replace the entire module in a larger refactor later?
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".
1. Is this code in production already making profit? 2. How often is this code updated? 3. Is it profitable to fix that code or just to learn from that experience and move on?