I just added 6 new titles from the current Christmas week sale to Mt. TBR 2019. I wanted to spend all 6 credits --and add 12 new titles -- but in the end I was lucky to find 6 titles that grabbed me enough to want to read them. But, sometimes they add titles toward the end of the sale and I'll check again before it ends.
In the meantime, the librarians are going to have a busy week because I am adding books to my shelves and every single one of them will need some sort of update in DB.