u/Previous-Zombie-9812

I was building this black walnut top for a client and I saw a video in japan where they were doing these thick cedar stairs and they rolled out the back side with wood glue, the man said it prevents cracking and increases longevity but ive never seen any other examples of it. I did it here but I was just curious if anyone was familiar with this concept?

Bought at a garage sale but cant make out the manufacturer