The return rate on shuttles was pretty damn impressive, IMO. There was a point in the mid-80s where we were putting up several flights per quarter.
Once Challenger happened, NASA became bureaucrat heavy and risk averse. The results of that mindset are seen now in our dealings with ULA. They’re so risk averse that they just can’t get stuff on a pad under any deadlines.
Contrast that with SpaceX. They’ve proven they could turn around launches in no time, and they’re reusing their cores, something NASA couldn’t agree on. The real test will be when SpaceX has its first loss of human life. I don’t want it to happen, but the law of averages says it will. How they move ahead from that sort of failure will determine if they’re able to overcome the analysis paralysis currently influencing NASA.
They promised days turn around.