Back of the stage, big clock on a screen counting down 10 full minutes. It's an artistic thing (probably), also very useful. You won't have to miss anything going for a wee, for one thing, although it's still a race against time at the bar in some venues, who seem to have a policy of making it harder to get a drink than it was during Prohibition. We'd like to think the band have something that takes 10 minutes they like to do in the break as well. Boiling three eggs, one after the other, something like that.