Here's an off the wall thought, maybe it has nothing to do with punching technique at all, maybe it's simply a way to build reflexes, timing, etc in a very convenient way. As long as you don't get it in your head that that's how to throw a punch then it's fine. I do stuff all day that doesn't mirror punching at all but it doesn't hurt anything.
Member of DaJoGen MMA school under Dave Hagen and Team Chaos fight team under Denver Mangiyatan and Chris Toquero, ran out of Zanshin Martial Arts in Salem Oregon:,