I get into trouble whenever I try to do one of these hybrid improvs, where the original idea starts as an improv but at some point I do something so horribly wrong, that I decide to start over. From the beginning.
It becomes a case where I'd be better off just making decisions and then recording each section independently.
Instead, I end up in a loop where I end up recording the same beginning part of the song 10 times. And at that point, it really ceases to be an improv.