I currently do between 18 and 20 residential driveways and 1 commercial lot.
on average it takes me anywhere from 6-10 hours to go through my route. that's including drive time between properties and the road condition obviously affect the time as well.
yesterday I did a 2" storm in 6 hours. I don't see the point in loading your schedule to where your plowing for much more than 12 hours a storm. I know people like money but I personally am not gonna risk my health with lack of sleep for some green backs.
I take on enough snow removal to keep me busy for up to 12 hours at most.