Slicer blade got dull mid-service, had to switch tactics on the fly

Last Saturday during a 40-cover dinner, my mandoline blade just gave up halfway through prepping a case of beets for a salad special. It started shredding instead of slicing, and I had to stop everything to grab my backup hand slicer from the drawer. That cost me maybe 15 minutes, which threw off my whole 6pm plating start. I ended up switching to a knife and a steady hand for the rest of the batch, but my cuts were less even and a couple of slices came out too thick for the dish. Any other line cooks out there keep a spare blade in their kit, or do you just learn to read the signs earlier and swap before it gets ugly?