I dabble in framebuilding, and have been cycling for 25+ years...........

Splitting hairs is the correct analogy, half the time on lugged framests the geometry varies up to a degree within the same lineup (handmade Italian steel 70's/80's) due to how the tubes ended up in the lugs for that particular frame. The "Masters" built by eye and feel, and produced sweethearts by the score.

Some framebuilder in the 70's stated that he wanted to make a museum of all the human freaks out there that supplied him with angles and tube lengths for custom builds that were submitted via mail.

Anyway..where was I?