You mean north and south facing? Timewise it's not difficult, I attempted the north/south versions, but in the end it was mostly a stylistic choice to limit it to side directions due to the knockdown action for north/south directions looking too ambiguous (not as clear or comprehensible). A side view of the knockdown communicates what the action is more clearly to the viewer. This could also just be due to the limits of my skills to make it look clear enough.