From what I've heard from the SpaceX and ULA people I know (although there may be some sample bias because most of the SpaceX people I know quit due to the hours), that's not really the case. ULA is more of a 9-5 company, especially for union folks, whereas SpaceX is more of a 60-80 hours/week kind of place.
that's true, but during & after their layoffs a couple years back they imposed a 'not mandatory but strongly encouraged' 20% overtime.