I was watching one of Chechen's JJ in MMA vids and something occured to me. As a fan I have no idea, so I thought I'd ask. Is there a rule or even an unspoken rule amongst fighters about pushing a joint submission to the breaking point if your opponant tries to tough it out? Take the Matt Hughes/Royce Gracie fight. Matt gave up on his submission because he knew Royce wasn't going to tap. If Matt so desired, could/should he have broken Royce's arm?