I agree with Brad...this is an old one...as threads go...

Further, in concurrence with the comparison of "stick building" the entire general modalities of timber framing an "eyebrow" is more what you would find in shipbuilding or fine furniture making, even if the 50% or more of it is hidden...It's a different world to "general contracting."

I would also add, that much of it can and is done without a lot contractor type "measuring" (per se) as it would follow one of the lofting, templating, and/or "story poling" methods, reflecting levels of accuracy that you just do not find on most "modern buildings" built today in domestic architecture...

Yup, Billy/Sim's method is lofted/laid out full scale. So they (can be) fully prefabricated on the ground and lifted up as a unit.

And easiest way to frame is boatbuilding-style, with ribs. Mainly because the sheathing works far better. In contrast, winging it with stick framing with rafters is easy, but then sheathing that surface is ridiculous. Especially with plywood.

...from 14 to 23, I never touched a "tape measure," and lived in the world of templates, scribing, story poles and "lofting" from floor or wall.

First "eyebrow" was more "art and template" than ever the idea of measure and fitting studs and plywood. I so often watch in amazement (and amusement ) wrestl studs and sheet goods into place...Most of what the contractor does today is more out of "habit" than logic and/or "good practice."

These ancient traditions are simply brilliant in there simplicity, ease, and logic in acute accuracy...even with "green wood."