Another factor in disbanding and merging units, you're driving down the denominator in Guards limit calculation. Speaking of which, does that go by counters on the map, or is there a unit size consideration that factors in (does 300 Inf Div mean I can have as many Guards Inf Div as 225 Inf Div and 75 Inf Bde?)
That is true that a smaller pool, yields a smaller total of Guards. I intend, as Flavio notes the inevitable necessity, of growing the Soviet army back out. For now, though, it is undergoing a bit of a "pruning" so that the growth is a bit more controlled, and stronger.
According to the manual description, the size of the various guards units factor into the approximate ratio that can be guards at the various breakpoints in the game. Whether it is "linear" is unknown.
How many Guards, and Guards eligible, formations do you have?
On turn 40, I have the following:
45 Guards Rifle Divisions
1 Guards Rifle Brigade
4 Guards Cavalry Corps
1 Guards AT Art Regiment
1 Guards Mtn Division
1 Guards Tank Brigade
8 Guards Sapper Regiments
2 Guards Motorcycle Regiments
11 Guards Lt Rocket Regiments (note, these are always Guards)
17 Guards Artillery Regiments (of various flavors, but mostly RGVK)
So, I am actually getting close to my cap on units, at this stage. I have to admit that Toidi did an admirable job of harvesting Guards. I've got another couple of dozen Combat Units that are ready to flip, with an unknown number of Support Units.