Said no way to a gravel base under my shed until my neighbor in Tulsa showed me his 4 year old slab
I always figured a shed just needed a few pavers and some luck, so when my brother in law pushed me to dig out and lay 4 inches of crushed stone for my 10x12, I shrugged him off. Then I helped my neighbor in Tulsa move his lawnmower out of his shed, which sat on a gravel pad he put in 4 years back, and the floor was still dead flat with zero heave. Now I'm out there with a shovel and a rake this weekend, so did you go 4 inches or deeper, and did you bother with a fabric layer under it?