Take your head and turn it 90 degrees to the left of center. Then, turn your eyes as far left as they can go. Through the miracle known as peripheral vision, you actually can see behind you without literally turning your head all the way around Linda Blair-style.
Aces High (and WW2OL, and AW, etc etc)inhibit peripheral vision because each snap view represents a smaller range of degrees than we would ordinarily be capable of seeing. So instead of thinking that the six view literally represents a complete 180-degree head turn, see it instead as a partial head turn with eye movement and peripheral vision taken into account.
In that light, I'm incredibly frustrated with WW2OL's unrealistic restriction on checking six.
-- Todd/DMF