Since there was no great effort made to coat the entire rear wheel well with body color only the areas hit with body color (while painter applied the paint to the important areas) would receive overspray,
So directly behind the fender lip generally would be bare metal or have some primer/sealer. out from that edge the overspray would start.
Just think of the painter running the gun down the side of the car (front quarter panel to rear quarter panel) and the over spray pattern that would have created on the inner wheel well and exposed wheel well) Then picture the painter painting the entire wheel lip and the overspray that would produce
Most of the time the amount of paint and the application is often pretty heavy - basically. just like the exterior of the car.
OF course this is over the sound deadener applied earlier in the process
Here are a few pictures I hope will help explain
