Very. Here’s a quick photo to demonstrate. It also demonstrates how important water is.

This was a tree with a big ring and fire pit. Got rid of the fire pit and now need to plant grass to shrink the tree ring. The stripe of grass is where I aerated and seeded. The area on the other side was seeded but not aerated. Both areas have had the same amount of water and all other variables. It’s been about 3-4 weeks since I aerated and seeded. I expect both areas to fill in completely by December.