A dull spare blade is just the universe telling you to slow down and get some arm exercise. My "backup plan" is usually a butter knife and a bad attitude, so you're doing better than me. Hand cuts win anyway, cleaner edges and you get to feel like a butcher from an old movie.

Had the same thing happen on a driveway pour in August, ground was so dry it looked like the slab was allergic to water. Now I keep a hose going on the base while we set forms and it's night and day on the finish.

Tag or test, never trust a 15 percent guess at 96 percent load.