The week I glued 40 signatures shut because I forgot one dumb step

Last Tuesday I was rushing a batch of 40 journals for a craft fair in Boise and glued every single spine block shut before I remembered to check the grain direction on the endpapers. I had to soak the spines in a damp towel for an hour, peel them apart with a dull butter knife, and re-sew 22 of them from scratch, which ate my whole Wednesday night. The funny part is the grain thing was a tip I picked up right here in this community three months ago. I now keep a scrap of every paper I buy taped to the wall of my shop with the grain direction drawn on it, plus a marker line on the cutting mat so I stop second guessing myself. Total damage was about $35 in wasted paste and linen thread, plus a sore wrist. Does anyone else keep a sample wall like that, or is there a faster way to eyeball grain before it is too late?