Re: How many practice Rokkyo?
Well maybe we should say that it is extremely unlikely that one would be able to pull off Rokkyo in many of the ways that it is practiced in a lot of places - such as when it is done as a Kihon Waza or Shu level training - outside of controlled environments. For example, if one were to jump from Ideal phase training like Rokkyo against a punch and/or against a knife to the expectation that one can defend oneself with Rokkyo against someone that is punching them and/or attempting to stab them with a knife - then, yeah, that would seem a bit delusional.
Still, Rokkyo is a viable technique, and like a whole lot of other Kihon Waza, it really finds its tactical viability when one transcends and/or departs from basic training and/or whenever one understands basic training in a way that is different from modern day scenario-based self-defense training.
Along the same line of thought - at our dojo we don't do anything empty-handed against a knife/tanto. Why? Because, even when we want to understand principles through our Kihon Waza, we can do so in ways that are not so "distant" from actual applications. For similar reasons, we don't practice Rokkyo against mune-tsuki - at least not the way it was shown to me by my various Shihan (e.g. uke comes flying in with an over-extended punch that remains thus as nage applies Rokkyo). Rather, we tend to study Rokkyo from fixated attacks (e.g. grabs) and/or when we apply it against ballistic attacks (e.g. strikes) we tend to have some other move, situation, event, or response, etc., that leads into the opening for Rokkyo.