[Jaybird]

when I was scanning multiple items, I'd make a couple of marks on the glass with a grease pencil to mark where the corners should go and then just place one card after another onto that same spot with great results. Just preview scan one time, adjust the scanning to only scan inside of the marks. No need to readjust for every card, just place inside of the white corner marks and press scan. Helped me cut down a bit of time. Then when finished, just wipe the marks away with a clean tissue.