Originally Posted by goodeats21

They are filled out when the mobile check in is processed...before the guest arrives. It is a "shortcut" so the FDC doesn't have to check anything on the computer.

Usually goes like this.

Welcome back, Mr. goodeats21.
Just to confirm, you wish to leave the room charged to the credit card ending in XXXX, and you would like points for your arrival gift?
Then hands over the keys, but keeping the little piece of paper.

I have noticed one frequent hotel where they wait to make the keys active (program the room number) until I arrive, which somewhat slows the process down. I will have to ask them about that sometime when I check in...