In my own personal experience from back in the day, a really, REALLY great press can leave the legs feeling like lead as the lactic acid builds and builds, and most players aren't real enthusiastic to leave themselves feeling that physically vulnerable for whatever happens immediately after the press either works -- or doesn't. The natural instinct is to conserve energy to make sure you don't empty your tank too soon, which is why Kellie should wisely choose the best time to ask players to risk that for her, and she needs to give them a shortish window to have to do it.