It is of the utmost importance to secure each load individually, regardless of the expected unloading sequence.

This wall fell because it had not been individually secured against shifting. The wall was not secured individually during loading, since it was going to be unloaded first anyway. During unloading, it wasn’t the first to be unloaded; instead, the outermost wall was unloaded first, and that wall then collapsed. It is of the utmost importance to secure each load individually, regardless of the expected unloading sequence.