If you are training for MMA/Boxing/Combat sports, shouldn't your session mirror what the competition is going to be? GSP recently stated that he doesn't train longer then 30 minutes per session as that mimics the intensity that a fight will be. If you are training for a 3x5minute fight, shouldn't you do 5 minute rounds? Is there any point of going to BJJ class for 3 hours? Lets say you come in, warm up for 15 minutes, do 15-20 minutes of drilling, and then do 15-20 minutes of rolling/sparring and then leave. The whole session lasts 1 hour. Is there any point of going beyond that? You could do that 5 times a week as opposed to going to a 2-3 hour class 3 times a week and having to take rest days due to intensity. You might even be able to go twice a day on some of those days if you limit it to an hour. Point is, besides doing long distance running, or a weight lifting session, is there anything that you honestly need to do for more then an hour at a time?