Radio Twins: The Second Law of Pop Musical Dynamics

Classic rock radio is usually terrible. The idiot DJ's, the repetitive playlists of the same damn songs over and over (Radar Love?, yeah I've heard it thanks!). One particular annoying fact, a law of pop music if you will, is that some songs are forever entwined in radio airplay. Two examples come to mind:

"We Will Rock You"/"We Are The Champions" - if you hear Queen's "We Will Rock You" you WILL hear "We Are The Champions." It is a metaphysical certainty. Why? I have read that radio stations in the 70s received a promotional vinyl single with both these songs on one side, making it very easy to play both together. If that is the reason, so be it, but radio stations switched to CDs a long time ago, and many use computer audio files. There must be more to it than mere tradition. I think this song duo must be the perfect length for a DJ to go to the bathroom, or more likely, fill out a Wendy's application.

"Heartbreaker"/"Living Loving Maid" - This pair of Led Zeppelin songs is also permanently linked. I like both songs but why-oh-fuck-why does "Living Loving Maid" always have to come after "Heartbreaker"? They are separate tracks on every Led Zep CD I have ever seen. Even on vinyl they are separate tracks with a space between them. The two songs were never even released as the A/B sides of a single. How about "Heartbreaker" followed by "Heartbreaker" by The Rolling Stones? No, that would be clever.