For someone who listens to the Christmas format carefully, it sounds like many songs get overplayed. But you don't want to play unfamiliar Christmas music, either. The whole reason we listen to Christmas music is to hear the songs we remember from our youth, played by our parents and grandparents during happy times. So I suppose Christmas stations will play the most popular songs every 3 or 4 hours. It's only for six weeks or so.
The playlist stays pretty much the same year to year. Each year a handful of artists will release Christmas albums. But the stations can only choose good, well-produced songs that are familiar. Six weeks are not enough time to introduce more than one or two unfamiliar songs. So the songs that can be played are new interpretations of songs we already know.
So often people will say, I hate when a radio station keeps playing the same song over and over. But then, we find stations that play the same songs over and over get the best ratings. So for the weeks it's in the Christmas format, Lite and other stations will keep playing All I Want for Christmas Is You, Holly Jolly Christmas and Sleigh Ride over and over.