In Star Trek, more TNG, we saw officers stay in the same rank and position for about 15 years (Riker, Data), without ever leaving. In TOS, we saw officers advance in rank (Spock, Kirk, Sulu, Uhura, Chekov, et al) and move into new positions (Rand, Chekov, Sulu). My question is, if Starfleet were to act more like the Navy, how would it act with regard to promotions and MOS? Let's say I'm a newly commissioned ensign in the Navy, what's my career path to captain of my own boat? And in parallel, what would then be my career path to captain of my own starship in Starfleet? In the Navy, if I don't advance in rank, don't I wash out? And aren't there limited number of slots for each rank? I'm looking to get a handle on how a real military would handle promotions and MOS so that I can write a TNG story, and also possibly do a TNG-era fan film at some point down the line.