You could also go into edit mode, delete the faces you don’t want, fill with F or use grid fill and that way start on that part with a kinda blank slate. But mistakes are always going to happen, and you wont noticed until is too late and undo steps will not be sufficient, so that is always I always save in increments, every milstone I feel I reach, I do a save as and leave a backup in case I have to go back. I has saved me a coupe of times.
