Don't get the "restricted playlist = better ratings" mentality. Didn't the success (in most places) of JACK-FM disprove that theory?
"Jack"/Adult Variety Hits formats have had varying amounts of success in different markets. They've done very well in some, mediocre to middling in many, and poorly in some others (it failed in NYC). That may depend on certain local factors such as an individual stations execution of the format, and what competition for the demo exists in a given market.
However, "Jack"/Adult Variety Hits playlists are not really the "unrestricted" "free-form we-play-everything" formats that they're promoted as. They're basically Classic Hits stations heaviest on primarily '80s and '70s pop hits (their core demo), dipping back to some tried and true '60s hit oldies, sprinking in a few more modern mainstream hits from the '90s and '00s, and occasionally throwing in something that seems oddball (such as a Country or Rap hit) to create the impression of "free-form", but if you listen frequently, there's just as much daily repetition of most of their songs as any other mainstream commercial format. It's basically a '70s/'80s pop hits core (which includes mainly classic rock hits and some R&B/dance/disco hits) with some occasional odd stuff thrown in around it once in a while.
Unlike "Jack"/Adult Variety Hits stations, Classic Hits and Oldies stations still depend on the predominant demo that wants restricted playlists, and wants to be sure to hear one of their tried and true favorites each and every time they turn on the radio. They're not the "Jack" audience that might enjoy something odd thrown in once in a while.
