From what I gather, the more you keep the intensity up, and the harder you push yourself, the stronger you will become. Use the 30 secs to rest your abs/upper thighs, and superset pullups, pushups, ect...in that 30 sec interval. Keep the intensity up! You could also do planks for the 30 secs...some ideas if you really feel like killing yourself. Ideally, you want to increase sets to the max (15-20 sets of what you're already doing--30 sec break is fine). Work towards being able to continually put out solid 25-4 counts when everyone else is toast. Either now or later...better now.