If you’re throwing a hard rock festival in 2021, the formula appears to be this: two nights headlined by Metallica, one topped by Nine Inch Nails, and another topped off by a nu-metal brand name. That’s how Louisville’s Louder Than Life is doing it, and Daytona Beach’s Welcome To Rockville has followed the same template, but with Korn swapped out for Disturbed. (Less “boom-na-da-noom-na-na-ne-ma,” more “oooh ah-ah-ah-ah!)