Everyone has been doing this long enough to know a few things:
1. When KEZ plays Santa 24/7, their audience does not scatter to other stations to escape Wonderful Christmastime, or if they do there's enough cume coming in to replace them that they still win.
2. When other stations try to muscle in on KEZ's turf the gains are limited because KEZ has been playing holiday tunes since 1996. They will own this position until they give it up. And they won't.
3. The whole business of playing 24/7 Christmas music screws up the market so much that the Holiday book gets thrown out by most buyers.
4. Knowing point #3, KEZ will jump the shark as early as possible to get a bump in the last couple of weeks of the November book.
If I were sitting in the PD's chair at The Oasis, the argument I would be having would be trying to decide which was more beneficial: disrupting the market by going early or continuing to re-image The Oasis away from being the station that plays The Pina Colada Song. Since you know that KEZ would flip within 10 minutes of you and they would get the early ratings spike in November, I would lean towards continuing to re-image the station as the "at work" station and carry on with nudging the format younger. Because the later in the month that KEZ flips, the less it disrupts the November book.
But I'm not sitting in the PD's chair at The Oasis, so they could have a totally different opinion.