Rupert Atkinson wrote:
Not in my exerience.
It boils down to the word "proficient", I would guess. O-Sensei showed that he could manifest that same (or better, if you count the jo trick) kokyu skills that are in Tohei's "ki tests". Shioda could do them. Abe could do them. And I'm sure there' s a number more that I don't even know of. If you can do one of the simple ones, let's say for example standing weight on back leg and partner pushing forearm, and you refine it, you should be able to realize and do most of the others fairly easily. Even "unbendable arm" is really just a version of the push-on-forearm one and can be done just as relaxed.
If your kokyu for a kokyu-nage is fairly clean and correct, it is from the same power as the "push on forearm" example. If it's not from that same relaxed power, then it's something else other than good kokyu power. If it is from that same power, then doing almost all the "ki tests" is easily in your reach. And remember, I keep mentioning "gradations"... I'm implying something about the "purity" gradient.