How many times do you scrap your code because you found a more efficient/better way to do things?

My current project is on it's 3rd iteration. obviously adding new features every time I redo, but the first library I used was too slow, the second attempt was messy and threading wasn't doing what I wanted. my current one is closer to 3.5 than it is to 3, changed up the code organization to be more efficient with the library I'm using. Debating on redoing the whole thing again to align with the new code organization but it won't provide any performance benefits, just look better for me lol. How about you? Do you scrap code when you find more efficient ways to do it? I am using python for my current project, with lots of calls to C &C++ libraries.