I think they change recoil over time, but your shoulder is still receiving the same amount of energy but perceived recoil may be less with a pad compared to a hard butt. How do I know, I just had shoulder rotator cuff surgery and I’ve tried EVERYTHING to reduce recoil. It’s hard to beat physics, Force = Mass x Acceleration, period. But, if the pad weighs more than a hard butt, it would reduce actual recoil slightly.