Yes Mike, that is my understanding of Dr Schmidt's method. I also agree that for most situations this is getting into the realm of navel contemplation. Just another tool for the toolbox. The oddball sizes come from my metric conversion. I was mostly looking at the trends to see if they agreed between practitioners.
Reading Jonathan Shanks papers, in green oak he was down to 1.5D mortise edge spacing using 3/4" pegs and said all failures were in the pegs not the members. I can see more peg failure in smaller sizes. This method of conversion from steel specs to wood is probably not so easily linear, simply for now a closing approximation on the way to reflecting reality. His graphs were interesting, wood pegs failed nice and slow. Even after failing the broken pegs had to be drug through the mortise and withstood a pretty healthy load.
Good stuff from Ben Brungraber's article; Keep the peg low in the tenon so that when the tenon shrinks it won't be hanging on the peg. Don't spread pegs more than 5" apart to avoid splitting wood as it shrinks. His article predates the others by about a decade so I think there is also some evolution of thought. He was presenting at the conference where Jim and I heard Dick Schmidt present his method as was Buddy Showalter from the NDS. Buddy did acknowledge that more research was needed in this area. I've emailed back and forth with him not too long ago and they, like so many of us in construction, have been through cutbacks and tough times that I'm sure will delay projects.
I digest slowly, lots to think about, as with anything the more you look the more there is to see.
I like the thread idea Thane.
