Yeah, I do it a lot at those times too! And I definitely will have whole sections (...usually in the middle) that are mostly like 'stuff happens here? I think?' or 'some kind of action scene, maybe tentacles.' But I get the impression than paper-draft people do that sometimes too. :P

It can change a lot for me as i write, but usually the scenes I spend a lot of time polishing do end up in the finished fic. (But that may be because I'm just not as good as you are at letting them go when I need to.)