In one of his movies, in 1971, fight icon Bruce Lee defends against an armbar in a manner somewhat, shall we say, cinematographic.
http://www.youtube.com/watch?v=SMK1W3oTLPg
Action-movie persiflage aside, what is it Bruce Lee teaches in this scene? He teaches, among other lessons, that an armbar should be practiced repeatedly so it will be performed just right. Otherwise, in a real fight situation, you could leave an opening for your opposer to defend, with tooth and nail. More tooth than nail, in this case.
“At the gym we always teach that, first of all, bites don’t win a fight,” stresses our GMA Guilherme Valente, of Gracie Miami. “Now, for a practitioner to eliminate any risk of a bite, what’s important is that training always be geared towards self-defense. That’s our main objective. We teach and train with that in mind. Just as a competitor’s thoughts are on the points associated with each position, we concentrate on possible vulnerabilities, like bites, in each movement.”
Valente thus concludes: “The armbar during a street fight should always be carried out quickly and decisively. The leg should always fit up against the aggressor’s neck, just below the jaw, and the other on his chest. It’s important to remember that a layman’s reflexes during a fight are completely different from a Jiu-Jitsu practitioner’s.”
So remember Bruce Lee. Talk to your Jiu-Jitsu teacher about how each move is best adapted for self-defense, and be a more well-rounded practitioner.