As Bill and Ted would say, "Strange things are afoot at the Circle K." I am shocked that there is so much FP availability for Christmas week, when Labor Day week was a bit of a nightmare. I don't think hours can explain it all, as we had a few midnight close (with 2 am EMH) days where there was still not much available.
I looked at our five days over Labor Day (and taking out EMHs where you can't get FPs anyway), and here are the number of additional hours the park is open for the five days after Christmas compared to Labor Day weekend
AK: 8 hours
HS: 4 hours
EP: 7.5 hours
MK: 13 hours
And I'd argue that there are really only a few additional MK hours when you're talking about A&E. Most of the additional time is the 11 pm to 1 am time period. I highly doubt that most people with little kids would be really excited to get FPs for 12:45 am, so I'm guessing most of the people who reported success in this thread got A&E and SDMT FPs for reasonable daytime hours. If that's the case, then I am really doubting the "parks are open longer theory."
My personal suspicion is that they held back FPs in the fall for some reason. I don't think they dumped a ton extra in for the holidays, as long FP lines would not be their goal. We had no problems get FPs for June on crowd level 8 days, but we had issues in August and September when the crowds weren't supposed to be above 5s. I saw lots of similar reports, and it seems like FP availability is suddenly good again. I don't know if they were testing something behind the scenes in the fall, but it sure felt like it.