I'm pretty sure you don't need to do it to get 100%. In fact, I'm sure as after a while you stop getting calls to go steal from it.
Event Horizon
does anyone know where the girlfriend is who will let you get out of jail free and keep your guns?
You find her in the Police Station at El Quebrados, Tierra Robada. She's in the Parking Lot. If you get busted in that area, you also Spawn at her place.
KM
I also had another couple of strange things happen while taking over gang territories.
First thing was that after I got the message "You have started a gang war!", the rival gang members all spawned right beside me. About six of them just materialised on screen and killed me within about 3 seconds.
Another thing that happened was that the rival gang members spawned about 4 territories away. I tried to chase them down but I got a message after a while telling me I'd quit the fight... Pfft.
Yeah, we've discussed this sort of thing before. There are a few little happenings, although that's the first I've heard of a gang spawning right next to you. Also, take care when taking over Territories on the Beaches. They spawn in the water, and often can't get out.
Also, as for the spawning four blocks away, that happens a few times with the Vagos. Just wait for them for a while, if they don't make any advancements after a while (check the Pause Menu Map), then take a Car or Bike (don't forget to take one with you as everything stops spawning), ride or drive up there, and drive-by them quickly. Do this very quickly, as being out of the "War Zone" too long will mean you have failed and quit the war. It's annoying, but doable.