I’m just speculating here… but suppose a station were deliberately out of phase with most other stations. When other stations go on break, frustrated listeners would search for different stations and find the out-of-phase one. They’d listen to that station until its next commercial break, at which point they’d repeat the process and return to their previous stations. The out-of-phase station would get a reputation as the station for listeners who always change stations at ad breaks, which would make it impossible for that station to find advertisers.