Ah, so that's why "you can have any color as long as it's black". And wikipedia agrees with your conclusion: > Soon, companies had to have assembly lines, or

Ah, so that's why "you can have any color as long as it's black". And wikipedia agrees with your conclusion: > Soon, companies had to have assembly lines, or risk going broke by not being able to compete; by 1930, 250 companies which did not had disappeared. It also notes iteration in the perfection of the assembly line itself, though going by its older name of trial and error.