Something that I've often heard from mid level blue belts directed towards some enthusiastic whitebelt is, "You're not supposed to do that" or "That's not a good idea" or "Don't do that from inside the guard" usually directed at someone trying a choke from inside the guard, or holding a guillotine attempt after their guard has been passed, or driving a forearm into the throat from inside guard. These are things that we know are 'wrong', but WHY are they wrong?
Well, they are wrong because they get you submitted or swept, right? But what if you, the blue belt telling this white belt that they are 'doing it wrong' can't actually get that sweep? What if you can't make the transition to the armbar? Is it really wrong for them to be choking you inside your guard if you can't do anything to stop them?
The answer is NO. It's 100% correct for them to do it to you if you can't prevent it. There are no wrong techniques in jiujitsu, only things that work and things that don't, If it works then it's not wrong. When it stops working, then it's wrong.
Just something for all of the blue belts to keep in mind next time they think about telling some enthusiastic noob that what they are doing is 'wrong'.