I promise there's a point to this even though it's out of the blue: When you were at Millionaire how long were you at the location? Did they have you practice the walk-on, where to stand, how to give your answers and what not, and how long was the down time? (I recall reading that The Chase had a whole lot of that.)
We spent about a half hour or so on the set for rehearsal. This consisted of each of us (there were about eight of us) stepping up to the plate to answer one practice question, and the rest of it was us just listening to instructions. We were explained how the walk-on would work, but we didn't physically practice it. Other briefings, mainly on what not to do, were done in the green room.
Obviously all the briefings took place on the first day for my session, which started around 9am. I was turned away about 1pm when it was obvious I wouldn't get to the front of the line in time. I reported on day 2 about 11am, and was immediately ushered into the waiting room right outside the studio. Someone else was taping an episode before me. I don't remember what time I was finished. Probably 1pm or so.
I was not in the studio except for when it was my turn, so I can't speak to how much downtime happened between episodes or during other people's games. As far as I know, there was enough downtime to shuffle the audience around, and not much more, and my game was about as close to real-time as you can get.