Jan Heine wrote:
"Sort of like 2 x 4" lumber today - nobody is too bothered by the fact that it measures neither 2" nor 4", but 1.75 x 3.75" or something like that."
Only a carpenter/ finish carpenter would be bothered; a guy that does it for a living. Just like a frame builder. But those guys sometimes tell stories that might lead you to believe otherwise.
John T.Pergolizzi Brooklyn, New York Former carpenter/ finish man; retired. Letting someone else measure twice , cut once. But still 16 inches on center.