With the case of the US Navy and the well-publicized collisions with civilian vessels, it's happening more because the organization is trying to run more ships and more constant operations with fewer people than are actually required.

And that's on top of scheduling practices that are fundamentally negligent and dysfunctional to start with, like watch standers (whose job is to watch for and react to dangers to the ship) trying to perform duty shifts on 4 hours of sleep a night for months at a time.