Unpopular opinion: grain direction on spine liners might matter more than the glue you pick
My old boss Ray in Cleveland told me back in March that he runs all his spine liners crosswise to the spine, never parallel, and I told him that sounded backwards for a book that opens flat. He said try it on 12 books and see, so I did, and honestly the crosswise ones cracked at the hinge joints way sooner. Now I can't tell if I proved him wrong or just used the wrong paper weight, maybe both. What's your rule for liner grain, do you follow the spine or the board?