It's a time I look forward to, these days between Christmas and New Year's Day. I have always labeled them the intercalary days, though where I got that I am not sure. It's nothing to do with the Christian liturgical calendar. Liturgically we are in the 12 days of Christmas, although the 12 days this year will be only 8 days, with the Feast of the Epiphany, (when the Wise Men showed up), disappointingly moved to Sunday the 2nd in the U.S., instead of the traditional date of January 6th.
Top Google results identify the term as a Baha'i concept, but I have some idea that I got it from the Egyptians or the Mayans. Still, the Baha'is have pretty much the same idea that I do, though their intercalary days precede the Spring equinox, not New Year's Day.
The intercalary days of Ayyami-i-Ha “stand apart from the ordinary cycle of weeks and months and the human measure of time... Thus Ayyam-i-Ha can be thought of as days outside of time, days that symbolize eternity, infinity and the mystery and unknowable Essence of God Himself.”We sense the stillness of the pole, around which the great world revolves, that does not itself move. It's a time for silence, recollection, rest. Dreamtime.
Libraries do a kind of "stand-down" during the Winter break, largely because the schools are closed. University libraries typically suspend interlibrary loan during this time. Public library bookmobiles are often off the road for a couple of weeks. Program rooms are mostly unscheduled and empty. Many librarians, of course, are mothers with children out of school or home from college, so libraries tend to have "skeleton crews" during the break. As a recognition of this, these are dress-down days. Many of us are in jeans and sneakers.