I remember a course with Chiba Sensei, about 1990 or so in Wales, in the UK. He showed a technique (it was a shiho-nage variant) and after awhile stopped everyone. He then asked a few seniors to demonstrate it and they all did something different. He went nuts and screamed at them. Then he showed the technique again and deja vu. I really enjoyed seeing senior teachers get a rollocking but I do not know why they could not copy what he was doing. He even said, while ridiculing them, that the white belts were trying to do what he had shown, and he had a pair demo it. He was mad as hell. Bizarre.
I saw the same from Kawahara sensei in more than one seminar in Canada. I used to watch very carefully to see what he was doing so I could at least attempt to do what he was doing, and remember on more than one occasion being "corrected" by others only to have the others rained upon from on high by Kawahara because the "corrections" were wrong..