David -

Funny this, I am somewhat confused by half scribe systems and systems which require what I see as the tedium and burden of material prep. This in part because I've used timber from some of the best tuned sizers on the planet and have seen them fail to true up bow and wind, something Plumb Line takes care of easily without the delay or expense of materials prep.

I've also spent alot of thought on the probable influences that led to the development of Square Rule, and have worked to research its genesis.

I also have come across some very early oddities that hinted at glimmers of either mass production or gains / reductions, sparks in that development - A Sixteenth C. English barn (sadly sent over here on spec, but happily a huge influence on my career path) which had universal square mortises for the up end of the riven studs sized to the largest of the varied size studs, sort of square rule thinking in reverse - And a Seventeenth C. New Jersey Dutch barn (though not a NWD typology) which had counter hewing like flattings at most all timber ends to aid in scribing which were far deeper and refined than is the norm, which appeared almost reduction like in appearence -

Such refinements and thinking were I believe, part of what in time led to methods of universality and mass production and in time the great shift to square rule.

We're all still looking for our Rosetta Stone in this little mystery of who, where and when.