Is anyone able to explain to me how contestants for a number of quiz shows on television are able to take indeterminate periods away from work to appear on certain quiz shows, in particular Deal Or No Deal and The Lottery Show quizzes?

It seems contestants have to commit themselves to an openended period of time away from whatever employment they may have, which leaves me to suspect either such contestants must be unemployed or in such employment for which there is little demand.

Can anyone provide me with an explanation?

-David Robertson, Lancing