True. That said in any non-trivial project, writing in the first place and rewriting aren't too different from each other in practice. Assuming someone doesn'

True. That said in any non-trivial project, writing in the first place and rewriting aren't too different from each other in practice. Assuming someone doesn't have the ability to maintain a consistent and always-accurate mental map of tens of thousands of lines of code, most of which they probably didn't write themself and some of which they might have never actually looked at before, they're going to very rapidly reach a point where most of the work involved in adding a new feature consists of reading existing code to understand how it behaves and how the new code needs to interact with it. So the expensive part of adding new code to a work in progress, and the expensive part of rewriting existing code, are more-or-less one and the same.