I guess it's horses for courses. I make a lot of biggish oak truss roof frames so the system suits me. Of course I use other methods when required, though since I have no hardstanding outside my workshop, just about a foot of oak chippings, I can't chalk on the floor..

I just looked at the index for "Timber Framing" and could find only one reference to trig: "Trig for the perplexed"! However, found some refs about trig in the "Joiners Quarterly". Can't recall anything in UK journals, but since I'm working across the range of woodworking, can't read 'em all!

Anyway, you guys have impressive and almost intimidating knowledge beyond my experience of framing at any rate. I just wondered if anyone had stumbled on the same system as me, by whatever route.