Totally Agree. If you try to use sandpaper too long (past its ideal life), you are just hurting yourself. A piece of 80 grit that is almost worn smooth will slow you down a lot! If a car has several paint jobs on it, I guess you could hit it with 40 grit to take off some paint, but be careful. I would either just use lots of 80 grit or use a chemical stripper.