Just like bodybuilding, different things work for different people. I tried clamping, worked my way up from 3 x 2 minute sets to 3 x 8 minute sets and got nothing. I went back to doing 5 x 30 second ulis and horse 440's and I gained. If I work girth every day I overtrain and get nothing or even lose size. Girth work 3 times a week is enough for me. Gotta try these things and make the mistakes to learn what does work for you.