When you reach revision Z-99 , it's scrap . ( or too small to see )
When I took the conventional machining course at the local college, the 1st project was a ball peen hammer. One of the students screwed up pretty bad on one op, the instructor at the time said, that's ok, being the 1st project, doesn't need to match the dimensions on the print, just redo what you got, no need to start over.
So he continues to tell us a story of how one of his students kept messing up over & over and his hammer kept getting smaller & smaller. Then he showed us a tiny little hammer on his keychain & said, "this is that hammer".
I don't know if the story was true or not but I'm assuming it didn't actually happen that way. This is not the actual hammer, stole this pic from the net, just to give you the picture. He was good story teller & a good instructor (I thought), I miss that guy.
These were the actual hammers we made, the other one is my lil bro's. He wanted/needed to take the class for one semester, I was his ride so I took the class with him but continued on to finish the course. I still have the hammers, never used them for their intended purpose though.