More and more missions contain dynamically spawned enemies, which makes difficult to predict the direction of an attack. This is very good.
What's not so good, is that my AI squad often gets attacked from behind and, at least partially, killed when stationary, because no one watches our back. Issuing individual "move to" and "watch direction" commands helps, but sometimes there is no time to play with that.
Such all round security formation would place subordinate soldiers in a circle, with guns facing outside, while the leader and medic would sit in circle's center. Leader would provide command and overwatch and the medic would be free to treat any wounded soldiers. This would be a stationary-only formation. The leader could go on a recon, but the rest of the squad would stay in the circle and be prepared for the unexpected. Before moving out, it would be necessary to order another formation.
A more simple solution would be to have soldiers automatically turn to provide 360 degrees overwatch and security, while stationary in any of the available formations. Currently they do slightly turn to secure flanks, but there is still a non-covered arc behind the squad. A one man to watch that arc would be enough.
When walking in Aware combat mode, a last man in the formation should periodically check what's going on behind the squad and then rejoin.
AI squads also should employ all round security and last-man-overwatch procedures, when in Aware combat mode.