My wrestling coach in high school was very much into the repetition game. We'd go through hours of nothing but shoots or escapes or whatever was on his agenda. When i tried BJJ 35 years later my shot was back after only a couple of practices. Problem was being in my 50's it was a lot scarier to do then than in high school. Even though I don't train any more I still work it on the heavy bag, I just don't finish the drive.