I don't extend my arms forward, but I do let the reins slide through my hands. I just didn't know what you meant by "sliding back"
Just a different way we were taught I guess. The main thing is that "whatever" I'm doing , I'm getting a better seat and better rein control now. My seat has always been good until the reins rattled me. Now I've noticed my hands are working indepenently of my butt.:')