How often, in your life, did you write code without stopping, in the middle of writing, to go back and review assumptions that turned out to be wrong?
I'm not talking about "oh, this function is deprecated, have to use this other one, but more "this approach is wrong, maybe delete it all and try a different approach"?
Because IME an AI never discards an approach, they just continue adding band aids and conditional to make the wrong approach work.