Thank you for pointing that out. You beat me!
Now days Christmas ends on the first day of Christmas— of the old Christian Christmas.
Christmas always used to begin, universally, on Christmas Eve decorating the tree, the season of Christmas began on Christmas Day, lasting for The Twelve Days of Christmas.
As you said, truly, Christian Christmas feast days were adhered to by all.
I need to research when and why the modernist cultural shift changed out even the memory of all that Christmas tradition. Wiped out, generally, today.
Maybe because the secular world only cares about the secular aspect of the Christmas season,that being the shopping.