My house was built in 1942 as temporary worker housing. I tore down and rebuilt one of the walls and the original studs were just astonishing: perfectly straight and not a single knot in them anywhere. Compare and contrast with modern studs from Home Despot: split, shaped more or less like a pretzel, and 50% knots.

Interestingly, these old studs were 1.75" x 3.75". I never knew there was an intermediate stage between the old-time true 2x4s and the modern 1.5" x 3.5" 2x4s.