And it's really surprising how few people realise that, even if the "quick" approach is slower in the long term, time is not always worth the same!
Time just before release is precious. Just after release, instead, you are both tired anyway and still have your code in your head, so that is the right time to refactor.
In the end, technical debt, code quality, and whatever code metric... they only make sense for code that has been shipped. The code you are refining is worth nothing if users are not already using it.