Starting month 20, there is 8*2 = 16 % chance per cult to spawn a Manor. The spawned manor has 80 % chance to be level 1, 15 % to be level 2 and 5 % to be level 3. AlienBaseUpgrades is defined so that after 5 months, the chance of getting bigger is 30 % and after 10 months it's 100 %.
The chances of even getting HQ Base missions and capturing a commander depend on RNG. In my current game, at month 22, I haven't had any exalt or dagon missions where I would have the chance to go for the HQ afterwards; I only got Black lotus shrine a month ago (all of these after some 9 months of waiting for them). It's really weid that I should have had 6*4 = 24 % chance at these missions per month.
Is it really fair that there is a chance (even a small one, ie. 0.8 % per cult per month) of spawning directly the greatest manor (with MIGs to guard it) even if the RNG has not even offered you a chance to take down the cult yet?
I'd suggest considering some alternatives, for example:
- greatest manors start spawning directly only after you have reseached the specific cult HQ, but have chosen not to go for it to contain it.
- great and greater manors keep spawning, and they might upgrade a bit earlier to the greatest manor if you don't deal with it quick enough. (There is of course a slight problem of not noticing that a manor even exists somewhere on the globe, but often you get some missions that give you hints or fly by it at some point.)
I would also suggest increasing the chance for CultBase* missions slightly (for example, up from 4 % to 5, 6 or 8 % each) to make it more likely that you'll get the base mission soon after researching the cult operations. After all, if you don't like it, you can just skip it or go there and abort the mission, no harm done.