Do you think Starfleet is limited by law as to the number of Flag Officers?
I remember reading somewhere that the U.S. NAVY is allowed by law so many Flag Officers (216).
James
I'd be surprised if such limits exist.
Lets put it this way - if you see Federation population as around the trillion mark, then if as little as 0.1% of the population are in Starfleet (a far smaller proportion than the modern USA) then Starfleet has almost a billion officers and men.
If we worked up the proportions based on your figures then the US Navy with 331,000 officers and men is a tiny fraction of Starfleet's size and so we can expect Starfleet to have literally thousands of Admirals.
This does not tally exactly with the on-screen evidence from the Dominion War, where Starfleet seems to have at its peak strength around 15,000-20,000 starships, and presumably far fewer in peacetime. Even with an average crew of 500 (which is probably too big) then only 10 million officers and men would crew those ships - so it is unlikely even with a large marine division, a lot of administrative staff, people manning subspace relays etc and other staff that starfleet numbers more than 100-200 million officers and men.
Therefore it is quite the elite organisation, employing only 0.02% of the Federation's population!