They film 3 shows per day. the shows are not acctually live apart from the saturday show. So if one contestant has a week of work they are in up to 15 shows. When you watch Noel never knows the winner of the home quiz unlike other shows.
Its like that with Countdown, they do a months programmes in one week, 4-6 shows a day, and have to be ready to wear poppies, etc for certain times . So the special guest only gets paid for one day instead of 5. Hence these people on Deal or No Deal are most probably just taking a couple of weeks off work and hoping to get lucky.