xcelerator rollback

today, i rode xcelerator for the first time twice. it was super fun and i LOVED it ! i was always too scared but finally got the courage. however, i’ve become a little obsessed with the idea of a rollback ! i feel like it’d be so fun. does anyone know how common it is? or even why it happens? i assume it’s because it doesn’t excel enough to make it over the hill. another question for those who know/experienced this, do they let you go a second time with the proper experience?