Southwest Rapid Rewards - LAX-OAK yield management via sale timing?

Last week I bought a bunch of LAX-OAK tickets on Internet Special. The schedule was open through September 10. Now the schedule is open through October 26. This is the second or third time in a row that the schedule window has opened right after the LAX-OAK sale ended.

Is this a coincidence or an attempt to limit the sale of discount fares in this market? If so, why wouldn't Southwest just block sale fare availability for the peak flight times and run the sales regardless of the schedule horizon?

The schedule opened to October 26th on the morning of May 3rd, a Thursday, so that was not before the weekly Internet special ended.