It seems obvious that there is a limit on the length and height of a group — so that it can be blocked by a guard (3 tiles) + the condition that other approaches are closed off by the landscape.
I've seen 2 Dragon Fly Hives + 2 resources behind one guard. And 2 Griffin Conservatories are so easy, that's like 2 chests in terms of value..
Осень-Зима 2013-14.