Surprise, surprise! RP is playing a second Spirit song after playing the first. Nature's Way followed by Animal Zoo. In 4 years of listening, this only the second time a single artist/band has had 2 songs in a row. Last time it was either Moody Blues or Neil Young. I personally like the variety; no genre has been left out. From 1920's Jazz, Bob Wills and his Texas Playboys to whatever is currently on the charts.
I like the way they will play a song by the artist/band and then the next few songs are covers of their work by other artists/bands. For a while RP was playing a Grieg every weekend. There is no computer picking the songs. Play another song is a stroke of genius-don't want to listen, then hit the play another song button.
To answer the question of how often repeated, send an Email with the question to RP direct.