Just saw this thread last week. Didn't ask the Skywest pilots because it seems to be a DL thing, but I asked the captain on our flight home. It was on an A319, and I got Card #37, an A320.

I didn't have time to ask how it worked, if they just had cards they could grab, if it was specific to the type the flew, etc. I saw him go up, dig a stack of cards out, and came back to row 1 and asked how many I needed. He also asked if I wanted a pair of wings. I chuckled and said "No, I'm not that young, and I'll just take one card please." At first I thought he said that tongue-in-cheek, but it later occurred to me that he probably thought I was asking for some for my kids (which I don't have any). I tried to approach him after the flight, but we pushed back from SNA late because the weight & balance was missing and for whatever reason, the GA had to open the cabin door and come on several times before we actually were cleared to push back.