Why can a slicer's rated speed be much higher than its actual output?

Rated speeds only hold for a defined product, temperature and slice thickness. Warmer meat, a shift in fat content or a thinner cut will drag real output down, and thin slices tend to stick and shingle, slowing the rhythm further. When comparing suppliers, look past the peak blade speed: have each run a sustained trial on your own cuts, at your temperature and thickness, and log the saleable slices per minute. Tie that measured figure to the blade set and feed configuration in the machine file, so future changes in raw material or thickness can be checked against it.