Instead of doing many Ctrl+Z. If you click Hold the current status is retained/remember by software and we can do as many different steps after that at certain point if we want to go back or not ok with current result, Just click Fetch the holded state will be back. This process avoid many Undo's.
You might also want to put in some step that breaks up the 100 Brush, Brush, Brush states if you want to be able to go back and know how far to go. ;-} Which is why I could like that Hold and Fetch feature if PS was able to offer something similar. (yes, I know you can take a snapshot, but that's more complicated to work with than this sounds like.)