This is mainly for Starfinder. My players are L4.
So, my players have set up a successful political party on the moon of Europa, which is currently in revolt against the Soviet Union. One of the PCs as well as some VIPs were recently captured on a prison ship, and the (PC) party has successfully rallied many other dissenting factions into putting together a strike force against said prison ship.
Now here's the immediate problem I'm facing. How do I balance the size of this strike force?
The strike force (not counting the party's private possessions) currently consists of 4 L1 ships and 2 L3 ships, as well as about 250 untrained conscripts. These numbers are quite arbitrary, decided by GM fiat (based on the L2 ship and the "hidden" L3 ship, as well of a crew compliment of 100 unmotivated shipmen) more than anything. If the players ever asked why I gave them this number of resources, I won't have much of an answer.
As a stopgap, I've provided the party with multiple objectives that are far smaller in scope but necessary for the success of the operation, like "here's a communications hub that would paralyze the defenders if a small strike team were to neutralize it" or "here's their commander, located in this particular cell block". This makes any potential imbalance no longer a problem at the moment, at least, but I would still like to know the proper solution.
Earlier in the campaign, there was also a similar issue. The party's resident Scientologist placed an ad on a newspaper, trying to recruit other Scientologists to act as spies, and to join his faction of Scientology. I provided him with 2d4 Scientologists per day. The player in question wanted more Scientologists per day and kept pressing it. I told him to buy a bigger ad on a bigger newspaper, but behind the scenes I was wondering how I could balance these resources. I don't know whether spending 250 credits on a newspaper per day should get him 2d4 semi-permanent recruits, nor would I be able to explain how much spending an additional 250 credits would work.
A similar experience (as a player) I had was in Pathfinder 2E, where we were about to face the BBEG's army whose size we did not know. After spending a day rallying our forces, we put together a force of about 3800 cannon fodder, which, as a player, was not much to work with since we didn't know how much we needed and how many resources we took to get them. Again, post-session discussions with our GM showed that this number was quite arbitrary because he did not know how to give us a "proper" number, if one even existed.
What are some concrete ways that I can use to say, "because you've spent X amount of days drumming up support at population centers of Y size and Z prosperity, you now have A amount of resources to bring against the BBEG"?
Any answers are welcome, but I would prefer Starfinder-based answers. Please let me know if more detail and clarity is required to solve this issue.