RE: Branding - Stay or go?
"All day" could also imply it's a 24-hour route, which it isn't. To be honest, they could point to the fact it says "UP TO every 15 mins" (hell, the Angel still says up to every 7; i think as long as there's a 7-minute, gap in the case of the 21, at some point in the timetable, they can get away with it)