So are you saying you actually took this waza from Shishida? What did it feel like?
It felt like I was given a small electric shock on contact with Shishida's wrist. Just before my grip locked onto his wrist everything from my palm to my spine locked up with an upward force that caused my head to whiplash a bit (in fact this happened to other folks in the seminar and gave some a headache). During that time my balance was "floated" upward as I had to go on my toes to maintain any balance. His wrist fundamentally became my central point of balance with me unable to let go even when I tried.
When he did the opposite and relaxed his arm I basically had my structure taken out from under me and dropped towards the mat. And I still couldn't let go.
It was a very interesting feeling of not being in control of anything. I grabbed him a few times to try to map out what was happening to me. That was 8 months ago and I'm still analyzing the data.
So as to your point about the "timing" - is that something that Shishida / whoever has explained and you're passing it along, or is it a discovery you've made by yourself and explaining as such?
A bit of both. He did show the timing, only once, from shotei awase, but did not explain it too much. He did the wrist grab version on me a few times so each time I tried to focus on different aspects of what happened to my body. I was able to link the two by drawing on my own research on this and was able to repeat most of the effect a few months later after lots of practice and relaxation. There is more but I am not sure enough about exactly what that is to post it publicly at this point. I don't want to bring Shishida's teaching into question from my own lack of knowledge and experience.
Still working on it. Hopefully it will make sense one day.
Hope that helps though.