Conveyor oven users- Do you use screens or pans or both?

Place that is leaving uses screens for pies and pans for the trays.
Wanted to see what you guys were using.I personally like the way their pans taste.
Also if it was the same,I used to use a light brushing of cornmeal on the bottom,but would be kind of hard w/ a screen.

-Also what are the differences between screens and the similar ones with the marble size openings?
Thanks as always.