I have a proposal....... at least hear it out BEFORE you say no....
So Faction A takes a town (Modoc). That starts a timer that prevents other factions from taking it in that time frame (24 hours?).
Faction B comes along inside that timeframe;
B's leader: "Bow down, I am your daddy" (stupid line, change it).
Sheriff Joe: "Sorry, but A is our daddy. You'll have to discuss this with them in, uh.... 4 hours (or whatever)."
That'll balance out the windows favoring certain factions WHILE allowing factions to reliably control the town for a timeframe.