I have had Pandora since it was new, and the algorithm is terrible. "B sounds like A, play it. C sounds like B, play it. A sounds like C, play it."
It doesn't rotate through the list of artists I've added to stations. For instance, two of the first I added to my classic rock station were Hendrix and Joplin, but the system hasn't played them in years.
This is why I don't listen that often. I like the music it plays, but it's only a tiny selection of the artists I've put into the system.
Is there a way to correct this?