I've missed a few flights in the past couple of months due to late arriving connections, and a few times the next flight had a long standby list, I know specifically there was one woman who had arrived late (her fault) for the 1st flight of the day, didn't get on the next, and was on standby for the flight I was trying to get on so she certainly got on the standby list before me. I got confirmed on a later flight but was the 1st (am Platinum) standby pass given a seat.

When I think about it, I think all 3 times I had to go with standby I was the first to get a seat (not in 1st class unfortunately but at least I got on)