i can´t say something about the percentage but: in the tool there is a Faction sub tab called "Squads" there you can adjust the min-max amount of roaming squads, towns, nests etc.i use the ingame inport option to increase roaming squads when i feel of need it, mostly i dont need only "one" squad to be more on the road.

You can adjust how many squads are spawned at a time, but one cannot adjust how often they are spawned.