The only reason that I can think is scouting the area better, but maybe that's not it? I wish the manual would give more flavour and explain things like that.
Answered this on the other thread. Effectively, the factions are discovering more crystals, so are doubling down to fight more. Somewhat like fightin over Norh Africa for oil reserves in WW2.
We do various elements of time dilation in the game for the sake of making the game playable. So, you create a battle, but don't resolve it until later in the round. In the fiction, the soldiers didn't shout "pause!" Focus less on when the Crystal is added, and more on: this region is very valuable, and swarming with enemies. We need another offensive.
I referenced avatar and I'll do so again. It's A movie I really like. The final battle scene is because the humans are trying to cut off the N'avi for their...crystals.