Another day's run was coming out. That would fill the bottom. The upper section was left open for taller models, and ones that were not moving right away. They also needed to be grouped together to keep track of the drying times. It also made it easier to order parts and lay out labor. Plus, the Hamer 4108 finish dries like a rock, so you could run back and forth with your hand, slapping them together and they wouldn't dent. Also, when they are closer together, the impact distance is smaller, so the force is a lot less than if they were wider apart. Plus it is a shorter distance to the ground if one fell than if it was on top. Other than that, I don't have an answer.
Bm