Like many artists in the smartphone era, Dave Keuning has “hundreds” of guitar riffs and musical fragments stockpiled in his voice memos. Some of these inevitably wither in digital purgatory. Some wind up on his solo LPs, including his upcoming second project, A Mild Case of Everything. Others are cherry-picked and presented to his bandmates in the Killers — a process that’s often trickier than fans may think. “I’ve shown quite a few things, and sometimes they just don’t stick,” he tells SPIN from San Diego, where he’s spent much of the pandemic “fishing around for ideas” at his home studio. “Being in a band can be awkward. I can’t make other people like my stuff. I’m way past the point of fighting about it. If they don’t like something, I’ll just try something else and save it for a rainy...