Every time you add a new feature you're basically creating technical debt in one way or another, often in a way which is not obvious until you've built a few additional changes on top. It's best to refactor a bit with every new code change. Most people I know never refactor, always say they'll do later, and then end up asking for permission to rewrite the whole thing, only to make a new mess
this matches my experience as a developer. now as a manager, i treasure those who can build most of their refactoring in as a "tax" onto every task, and then explain anything bigger that won't fit clearly enough - we can usually find a future initiative that could expand to contain and benefit from the desired refactor if it's actually a good idea.
