Or how about just show up to class and mow everyone down with an assault rifle? Or pump Sarin gas into the ventilation system and wipe everyone out before they even know you are there? Or throw in a flash bang grenade to stun everyone, then run in and start busting skulls with a baseball bat while everyone is disoriented.
Look, we get it, it was rough training, like I said I've done lots of that myself. But there were rules, period. Without ANY rules people would be going to the hospital and/or morgue every time you trained, you would run out of training partners really quickly, and the school would be shut down by lawsuits, insurance companies, or the state in very short order.