Thanks Jeffrey. I've seen some stuff posted by Ron and others, but it all seems to revolve around coding. I'll get to that, in due course (gotta get a reasonable looking ribbon first).

Another example came up just now. I thought that perhaps if I had multiples of 3 buttons in a group it would stack them, but there is absolutely no pattern.
3 buttons - all large
4 - all large
5 - all large
6 - 3 large, 3 small
7 - all large

But this is really only happening to the groups on or near the left.......

"AHA!" says I, maybe it's just the first Group is always large, so I put in a single button group as the first.

Nope.