I stumbled onto this in a Google feed.
https://www.thedailymeal.com/1347251/parchment-paper-hack-uncover-oven-hot-spots/
They suggest baking a sheet of parchment at 400 degrees for 20 minutes and using the color to judge the heat distribution. Pretty clever.
Ran this test twice. Once with a baking stone in the oven and once without. Neither test showed any hot spots. I already thought my oven heated evenly, since my loaves bake uniformly without the need to rotate them.