I think everyone is overcomplicating grain direction on endpapers
I keep seeing posts online and in workshops where people obsess over getting the grain direction exactly right on endpapers, like the book will fall apart if it is off by a fraction. In 12 years of binding books at my shop in Portland, I have used endpapers with the grain going the wrong way on maybe 20 or 30 projects, mostly by accident or because the paper stock I had was too nice to waste. Not a single one of those books has come back with warping or cracking, even after a few years on someone's shelf. I am not saying grain direction means nothing, but I think people stress about it way more than the actual durability of a well glued hinge. Has anyone else had good luck ignoring the grain rule on purpose?