The Wiki is often outdated in many regards, so 1/3 is true for all ranks. However I would really like some capability to customize this in a game. In my current game for example I had to introduce a Senior Captain rank, just because I wanted more captains, while the 1/3 rule would mean I basically get at least one Admiral type of rank per captain, and even some more later on. That is far too many admirals per ship captain if you have many ships and bigger fleets, and actually, even 1/9 would be too much if you use Commodore in between. On the other side I'd like to have only one marshal rank, so the ratio to that should be high (currently I am just adding a rank on top where there are not enough officers around to reach it, and then promote the leader per hand, which is fine too actually). Or in the ground ranks, I'd like to only have one general per real army, which I put artificially at 12-15 divisions.
So it would be nice to either have some custom control directly, or, as in the old wiki article, have some sort of differentiation between lower and higher ranks, but in another way. Maybe the "high-class" admiral type ranks start at 5 or so (would be best to being able to customize), so between 4 and 5 the ratio could one time be really low, like 1/20 or so, and after that normal again.