The answer is yes…and no! It all depends on your definition of “on call.”
Is it possible to be Batman? OK, better question, who could afford the technology to be Batman? Could we even make much of what we see being used by Batman in the Dark Knight movies?
At the time the space shuttle program ended, the three remaining shuttles had flown 25, 33, and 39 times respectively. They were designed for a lifetime of 100 flights each.