Preference in spawning location; crappie vs red ear and gills

One of the spawning areas I fish is a large shallow flat, with one deep hole off to the side. About half of this flat has flooded brush and tulles. I was asking myself "Why would the crappie and other panfish nest out in the open vs WAAY back in the brush that is inaccesible by boat?
Redear and gills don't seem to care being out in the open on a nest made of a few gathered shells, and having no quick access to deeper water. I notice where i have caught crappie in the shallows, it has mostly been in an area near a drop.

I think you will find, they will be back there too. I've seen guys way back in the brush fishing for big shellcrackers. I have to think bluegill and shellcracker get out in the open more because the water is a little warmer because there are no trees. I agree about catching crappie right on top of a drop especially early and late in the day. It may seem to be barren water but about 30 minutes before dark, they move up and it's on until dark.

My experience is that the shellcrackers will nest considerably deeper here in IL.