I understand the average debth is around 3\".. however that is after the plants are up. When we got our project started, I looked at using hay or straw, however at the time, it seemed like an added expense... when I was walking over leaf clutter already there that would do the job nicely anyway. Another consideration I had was introducing hay seeds to the woods, didn't want those in there at all.
And, there are different points of view on this. Some are looking at the ease that seeds push thru, others are looking at replicating the Wild Grown plant.
Our decision to grow in the manner we are growing is based on the end product result... which is to ethically represent our product as close as Wild as we can get. Again, it's just our approach. Many other folks do it differently, and I've no issue with them a'tall!