The trouble with code refactoring is knowing where to stop.
Updating a codebase developed over 15 years is a miserable endeavor. So much that made sense in 1999 really doesn't hold any water today. The trouble is, you can find this everywhere you look. "I really should do it THIS way, and while I'm at it best practice says do THAT tooARGGGHHHHH I BROKE IT!!!!"
Trying to find the sweet spot you just wind up with This Is Good Enough Move On.