Thats a huge rant that doesnt answer my question. If it's such a well known fact that the calendar can affect a movies performance than why would they release it that day?
That's a good question. Why don't you ask them? Maybe studios care more about the first week or two than they do about the long tail, especially for December releases considering they've long considered January a "dump month" and probably aren't hedging their bets on a holiday movie continuing to pull massive numbers after December. It could very well be the case that Disney isn't too concerned about whether or not a movie released ahead of Christmas takes a 10% or so hit to its box office because it released a few days too close to Christmas (and therefore also New Year's). Despite all the screeching from "fans" about TLJ's post-New Year's legs, nobody as Disney ever made a stink about it (at least not publicly; in fact, nobody has yet to provide a source showing Disney execs were "disappointed" by the film's performance at all).
But the simple fact is that the box office takes a huge hit after New Year's. Don't believe me? Here you go:
That should be more than sufficient of a sample size of December releases. Look at how every one of them has a big drop after New Year's. As I pointed out in a previous post, even a film like Avatar, which had anomalously strong legs for a 21st century film, had the largest week-over-week drop of its first two months in Week 3, the first full week after New Year's.
Is all of that data that not proof enough for you? It's all right there, black-and-white, clear as crystal. If you want, I can go through the trouble of graphing them and some big summer releases to show how the typical drops compare.
The. Calendar. Matters.