There are things you learn, and there are things you know. For instance, I knew that Paul Anka had written the song Johnny Carson used as his "Tonight Show" theme, and had composed it specifically for that show.
In my mind, that was simply a fact. Until today, when I read veteran sitcom writer/producer Ken Levine's post about paying for the rights to use music in television shows. After some anecdotes about songs they used on "M*A*S*H," "Cheers," and "Frasier," Ken finished with this:
If a song you write gets used as a theme song for a show you get royalties every time it airs. Paul Anka wrote this innocuous little tune for Annette Funicello in the early '60s. The record sold maybe eight copies, but Paul Anka will tell you it's the greatest song he’s ever written. Why? See if you can recognize it.