Ray was right and I learned that same lesson the hard way on a 6061 job where my vise had walked about 5 thou from a crash I forgot about. Now I re-indicate the vise and touch off every tool at the start of every job, even if it was running fine yesterday. Takes maybe 10 minutes and has saved me way more scrap than that. Trusting the numbers from the last run is how you chase a taper all day and blame the wrong thing. Aluminum moves, vises move, and your memory of what you set last week is not a setup sheet.

My buddy Dana runs a small bindery out in Beaverton and she had the same thing happen, 60 books, all warped, and she almost quit. What she does now is she takes a fat Sharpie and draws an arrow right on the edge of every board before she cuts anything, pointing the way the grain runs. Sounds dumb but she said once the arrow is there you can't ignore it, even when you're flying through a stack at 11pm. She also stacks them all grain-side up so if one is flipped you catch it before it hits the cutter. Might be worth trying if you're doing runs that big.