To reiterate what USMC said about the Marines I'll give an example.

In the Navy, to go through the TOPGUN course infers a two year commitment as a training officer after your shore tour (whatever unit sends you through). I know of Marines that have gone through the course (which is 10 weeks and about $2 million in training, depending on who you ask), to only be then sent on a 10 month IA as a JTAC or some other ground job. They come back a year out of the cockpit having lost all that training.

Similar to that is the way the Marines move guys around, at least within the Hornet community. It seems to be a total crap shoot as to how your career plays out. From the same squadron I've seen guys go through the full three years, get a full division lead qual, go to the RAG and instruct. Then another guy gets pulled half way through his first tour, sent on IA, come back to the squadron only long enough to get recurrent and never finish his division lead (4 ship) qual. This makes him totally unattractive to any follow on flying tours outside of the training command, and pretty much ends his Hornet career.

Obviously these are only a few cases and not an absolute, but really goes to show that you really are a Marine and a rifleman first, and everything else second.