Undo/ redo history
To undo or redo a few steps I use the undo and redo buttons on the top menu panel.
If I wish to undo further back I use the following method:
-Hold down the Shift Ctrl H keys to open the history panel.
-Scroll through history to select how far back to undo.
I find this very quick to go back to a certain point in editing.
The feature is great if you are trying something new and cannot remember the steps, you can go back and make a note of the steps. Or go through the steps one by one.
Close up - Undo History