I've been to the 2nd edition of Download Festival in France in June to see Green Day. Don't know if this would be very resemblant elsewhere, but here's what I can tell:
The festival lasted 3 days, Friday 9th to Sunday 11th; there were 4 stages: main stages 1 and 2, medium and little, so there could be up to 4 bands performing at the same time. To give you an idea of the bands that performed and the music genres that predominated: on day 1: Linkin Park, Blink-182, Pierce The Veil, Gojira; on day 2: System Of A Down, Slayer, Paradise Lost; on day 3: Green Day, Rancid, Suicidal Tendencies, Prophets Of Rage.
Green Day were the closing act, performing last on Sunday; when they came on main stage 1 at 8 pm, Prophets of Rage had just begun performing on main stage 2. So at first people had to choose between both, but as Green Day's set was longer, everyone could watch them by the middle of their set. Even though the audience were mostly hardcore metal / punk dudes (I managed to stick on front row all afternoon but it was really scary), and Green Day's music was a cut with most of the other bands, most people chose to see Green Day instead of POR from the start