This question already has an answer here:
Working on ads and pleasing your client is hard. Sometimes they will change they mind and would prefer the one you made on the 5th revision when you already revised it 10 times. And changing small things multiple times and saving the file gets frustrating. You forget the one you did from the 3rd revision.
How do you deal with this? For me, history panel is my friend in Photoshop. I recently discovered it can automatically save a snapshot every time you save it. But sometimes, its not super effective.