Pro tip: check the grain direction BEFORE you trim, not after
A guy at a bindery workshop in Chicago last spring watched me cut a whole stack of book cloth without checking the grain and just shook his head. He said "you just made 20 warped covers and didn't even feel it happen." That one sentence stuck with me because he was right, I had skipped the simple fold test on every single piece. Now I spend 30 seconds per sheet running the crease check and it has saved me from scrapping more than $80 worth of material since then. Has anyone else had a shop veteran call out something obvious that you'd been missing for years?