The way I view it, in the studio training your opponent could be considered "compliant", as Cord points out. But in a real-world fight, your opponent could be considered "unsuspecting". If you aren't advertising, they have no reason to know what is coming. The JJ move that makes your opponent do a flip in the studio will most likely break a real opponent's arm, because they aren't expecting the move and don't know how to fall properly. This is the main reason that I don't personally worry about real-world applications, this element of surprise.
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Be nice, until it's time to not be nice.