It seems a tricky formation to master from my limited experience. You have to allow enough time of the unit to settle down, facing the way you want, and you have to make sure you guard the flanks. I tried to use it to block the front of a bridge and my unit got massacred because I left it took late and did not anchor it enough. It's a little too static for my fighting style, I guess. I use the pause alot and micromanage to get good unit match-ups against the AI. The shieldwall and schiltron don't seem well suited for that kind of flexible fighting style.