I haven't ever listened to Pandora, but it sounds similar in a lot of ways to something that Yahoo had years ago, called Launch (or Launchcast). It was basically an attachment to their chat application, or could be viewed via a web browser (we're talking early to mid 2000's, there wasn't any "apps" at that time).
The way that worked was you could listen to stations that were made and hosted on the Launch site. They would have names that indicated the type of music played, but it didn't mean it was exclusively that band or artist. Something similar would be like on XM radio, there's a channel called "Ozzy's Boneyard". So, the style of music is similar to Ozzy and Sabbath, but certainly not even close to ONLY Ozzy/Sabbath. These were the same. You could also create your own station a couple of different ways. The way that I used it for my own station was I ran it directly off of my own song ratings. Ie; you'd likely hear a lot of Dokken, Metallica, Scorpions, AC/DC, Sabbath, Judas Priest, Motley Crue, Tesla, Queensryche, Dio, etc, etc because I always voted 5 out of 5 stars on those bands and albums. You'd never hear Nirvana, Radiohead or U2 because they'd always get the lowest possible rating from me.
Anyway, I had a paid subscription to this service for a few years and really loved it. Not sure if Pandora works like that or not. Anyway, I get what you are saying though, listen to one station for any length of time, and you'd find that it was basically the same 60 or 70 songs on shuffle.