I guess I don't understand why other people have trouble removing old paint

I'm no great shakes as a body man, but it seems to me that 36 or 40 grit discs on an electric D/A takes the old paint off about as fast as I'd ever want to, plus the discs last a long time and never clog up. It also does a creditable job of removing bondo.

When I start to see primer in the scratches, I might switch to 80 grit, but maybe not. If I am going down to bare metal, I will often just stay with the 40 grit until almost all of the primer is gone and I start to scratch the metal.

I never understood why people will try to remove old paint with 80 or finer grit paper. I guess it is because they are afraid of scratching the bodywork, but I don't think that is really a problem. 80 grit will clog up almost right away.

Your opinion, please?