Mm, that is all quite reasonable, Prince. I've never had any 1x1 partners, so in truth I wouldn't know, but I am convinced that the sweet spot between engaging interaction and manageable cooperative storytelling IS the 1x1x1.

If all three are equally compatible, it alleviates the worst of 1x1, and still retains the things that I have observed as lost in larger groups. It's a simple theory, but together with your points here it makes a lot of sense to me.