Years ago when I worked at Wallyworld, they were big on the risers......they had gotten a couple of pallets of the large Maxwell coffee cans, and decideded to load the first aisle with cans stacked about 10-12 rows tall......which looked great, for about 2 hours.......followed by some loud creaking, and a deafening crash as the entire riser came down.....all but destroyed the entire first aisle......Thankfully, the store wasn't open yet.....
They didn't really learn anything from it, but at least the next time they did it, it was with the cans of Danish Butter Cookies......not quite as heavy, but still heard a lot of creaking....
They never really did figure out why I refused to build risers after that (other than a single layer).....