I lost my patience with this show about half way through series 2 I think it was. Somewhere in amongst the 'push the button - don't push the button, I lost the will to live and haven't watched it since.
I am sure I am probably missing some great TV, I still wonder if the world actually WOULD end if the button was not pushed!!! But I found my attention wandering, and when that happens to me it means it's time to find something else to watch.