The real issue I can see running mixed sessions on the same day would be when cars dropping wheels and dragging dirt back to the track, but I see it being much less of an issues once curbings are in; and long term may be causing the brake zones at either end of the straight to get bumpy. I am classically trained at Loudon, riding tracks with shitty transitions and surfaces is my speciality…:rofl.
As it stands right now the track is very smooth, short of a few sections in certain corners, and the asphalt is very grippy.