But.............. They dont even know the "grab there leg" defense unless they somehow magically "feel" that that is an intuitive way of defending the head & arm choke.
I mean really, think about that for a minute. How in the hell is someone going to come up with that type of defense on there own?
As Balto pointed out earlier, I think by "reverse engineering" most of the attacks, aka good posture, you are going to avoid a lot more subs than a technique based defense. I remember learning the grab the leg defense during an open mat on as a white belt. I think I got caught in an arm triangle and was trying to pull my shoulder out of my neck some how. My instructor came over and said you can accomplish it better like this and it showed it to me. It took about a minute to show me and has come in handy plenty of times.
But I've probably avoided a lot more arm triangles by having good posture on the bottom of mount or wherever, and I've spent multiple classes working on mount bottom posture and escapes. I think BJJ defense is taught more like this and while I think teaching some late counters is good, its more important to spend time teaching being in good position in the first place.