However that requires your learnings to be complete (in respect of the code you are rewriting). My point is that for any reasonably complex code base of some ag

However that requires your learnings to be complete (in respect of the code you are rewriting). My point is that for any reasonably complex code base of some age, that may not actually be possible even with the best of intentions. There will be a corner case you'll miss, or a necessary optimization you'll leave out. Of course this is over a spectrum, so refactoring code that only you wrote quite recently is probably ok and indeed a good thing!