There's a reason people dismiss the calendar argument. It's completely ridiculous. The calendar isn't going to stop people from coming to watch your film, if it is popular and, more importantly, good. Sure, it can play with your drops somewhat, but if people can't come because it is Xmas Eve, they will just watch it at another time. Absolutely NO ONE is going to say, "Oh man, I can't wait to watch TLJ. Oh, but wait, today I have to go shopping. Well, I guess I'll never watch it, now."
Again, ridiculous to even act like that is a thing. No, what kills your movie's legs is putting out a mediocre/poor product and bad word of mouth getting out about it. There is no reason that an ok Jumanji sequel should have better legs than a main episode in what was the largest movie brand.