Sometimes switching up your workflow makes all the difference. For years, Illenium had always written music for “listeners” but when it came time to plan his Sphere show ‘Odyssey,’ he reverse engineered the process. “I didn’t have an album planned. I wasn’t sure what I was going to do,” the 35-year-old DJ told The Post in an exclusive interview about his Las Vegas residency from March 5 through April 4. “So, I made this album planning how I would play it at Sphere from day one. The first thing