My old mentor said to always round the spine corners before casing in, and after 40 books I finally get why
When I took a short bookbinding class at the community center in Boise three years back, the instructor kept telling us to round the spine corners on every single book, even the little 4x6 notebooks. I figured it was just fussy advice and skipped it on most of my early projects to save time. Fast forward to now, and the corners on those first few books have worn through and frayed while everything I rounded is still holding fine. Something about the turned-in cloth not taking all the wear on one point, I think, though I'm no expert on the why. Does anyone else round corners as a rule, or do you only bother on bigger stuff?