There's a difference in half repping weights because it is too heavy for them (watch kali muscle try to squat) and experienced Body builders using lighter weights but keeping constant tension in the muscle by working only in the minimal contraction and stretch zone. You will always get better gains dropping the weight down and lifting lighter weight like it was heavy, using a mind-muscle connection to move the weight, instead of just throwing it up. But most guys cant take this hit to their egos so I guess we live to strive somewhere in the middle?