Saw posts complaining that corps/alliances/territories are too large. Here is an idea:
Each alliance has HQ - the further an owned structure is, the smaller the timers on it. Or something else that makes it easier to capture or destroy.
Lore: some control signal gets weaker. May be a calculation taking both HQ and alliance HQ distances into account.
This effectively puts a limit on territory owned, unless a disproportionate amount of effort is put to defend.
Possibly also introduce penalties if surrounding territories are too peaceful.
The goal is to give advantage to smaller corps/alliances to grow up to a certain size.