I think I’ve sorted my confusion with this website’s teaching method, which is a tiny issue for me and probably not pertinent to most other players.
I set it out like this @Troy.
In the identifying elbow motion section on the website two forms of elbow motion are listed, radial form and straight form. There is no ulna form of elbow motion listed.
In the video below there is Andy Wood using an ulna form of elbow motion, although your dialogue seems a little equivocal.
Earlier in the same video we get this, which is a description of radial and ulnar devaition in relation to wrist movement.
So when I came to have a go at learning wrist and elbow picking, I found my wrist and elbow forms are both ulna forms. And I didn’t quite know why.
So I assume you are happy to have the elbow form with the Andy Wood video meaning there is an ulnar devation elbow form which is efficient.
However, where I got further confused and have sorted out with practice is there are I think two usable wrist positions, a radial start position and an ulna start position. I’m still not sure if this is in your clock face video or elsewhere on the website and I’ve missed it.
Unlike the now three positions of elbow motion, radial, straight and ulna, the website rightly does not say wrist has a straight position. In fact as far as I can see you can’t go through the middle of the arm with wrist picking, moving from the radial through the middle and to the ulna. This is slow and unpleasant and going through the middle produces a change in wrist angle.
So once I got the primary wrist motion for the ulna position as my start point and it became efficient, I found I could stop playing and very slowly in the air move my wrist throught the middle of my arm, ie through the middle elbow position although still with a little flexion, and find the radial form as a start point and begin playing again. And it was as capable as my ulna position form with no extra practice. Each start point is about a centimetre from a straight out elbow position with a little flexion.
It doesn’t seem to matter for wrist picking as long as you find one of the two starting positions, and most people seem to find the radial position, but there does seem to be uses of finding both positions in certain strumming.
I may be repeating what is already in the website here but this has been my experience in learning how to do and understand wrist motion.