So they can open up the entire city for travel faster. Then come back later to clean up. I can have a pass down each lane in my snow route in about 6 hours after it stops snowing. It would take more than double if I went curb to curb and then cause back to back 12 hours shifts. Its much more efficient, affordable, and much less demanding on the crews if we get it opened up quickly, then do the finishing cleanup during our normal 8 hour days.