The way FAF uses tree groups is just a walkaround from how ugly the patrol or manual reclaim mechanics work:
-For patrol reclaim: engineer logic is fcked and for some reason they waste of lot of time to pack/unpack their claw between reclaiming multiple things.
-For manual reclaim: 1) You wouldn't click every tree manually which allows engineers to reclaim without claw unpack animation 2) FAF rejected all sorts of area reclaim and consideres it game-breaking mechanic despite such things exist in other RTS. (nobody misses stone clicking there, but i guess in FAF clicking stones is so much funnier than remaining SCFA gameplay)
Instead FAF abuses attack move from factory - and that is actually a bug abuse which AFAIK didn't exist in GPG.
May be fix factory attack move and introduce proper area reclaim so people wouldn't waste half of their life clicking every stone on the map?
Some time ago it was more efficient to just break tree groups because it gave more mass, these days it better not to break trees because it is soooooooo much faster and gives more E. You have one number of trees, why do they give different amount of resources if they groupped of separated? All tree groups should automaticly break once game starts.