Yes, there is the shift work aspect, but you know in advance what your schedule is.
Just a tidbit of information. Glen Woodbury started as the first paid duty officer for Washington State Emergency Management Division back in the early 1990s. He ended up being the director for the division and now has a senior leadership position at the Naval Post Graduate School. He certainly had the skills, aptitude, personality and drive to move up. The other factor that is always critical is timing. He hit it "almost" just right. But, persistence led to his success.