Many schools in the Southwest don't end their Christmas/Winter Break until after Three Kings Day (January 6th, the 12th day of Christmas), especially those who have family in other countries, they go there to celebrate the holidays and don't care too much if their kids miss a few days of school. And since public schools get paid by the State based on a per student present per day formula, any unexcused absence costs them money, and the shift in the calendar was made to prevent these losses. But there are so many different school districts in the area (Heck, the city of Anaheim has 8 separate school districts for K-12 education), calendars do vary.
A similar issue with Spring/Easter Break, and some districts now get 2 weeks off, or for planning and educational reasons, have switched to a fixed week off (such as after 10 weeks of the semester). So the traditional week and before Easter Sunday tends to be the busiest, But Disney does start extending hours and increasing staffing from the 2nd week of March to late April.
So Disney does offer extended hours for the first week of January, due to the expected large crowds. Add to that the AP issues, with many locals having them and the blockout dates for some are lifted, you do get that double whammy.
