On the one hand, I have definitely had this experience - I rewrote a library three times, with large gains in performance, readability, reliability, etc, each time (but mostly on the third time, which was from scratch).

That said, isn't it also fair to say that with a better understanding of the requirements and problem, you may determine that a different language / paradigm is a better choice, in the same way you may decide a different class division is better?