Some of you who care about this sort of thing might be interested in reading
the BBC's policy regarding credits, which is up for everyone to view thanks to being a publicly-funded organization. Due to the Beeb's policies regarding "readability," what happened on "Celeb Mole" last night wouldn't be allowed, but there probably would be fewer credits. Feel free to go around and see how serious the Beeb is about their logo.
One paragraph on the "Programme Duration" page is on topic:
End Credit durations for programmes such as daily quizzes and continuing sports coverage should not exceed 10 seconds. They may be longer for first and last editions provided they do not exceed the timings listed.Which would be 25 seconds for your average half-hour game show--and that's 25 seconds of *readable* credits. However, if the show's on BBC Three, their new digital/satellite young-demo channel, credits are 15 seconds, no exceptions (and title sequences are 10 seconds, no exception).
And "first and last editions" means first and last shows of a season (or "series," as they prefer to say).