i used to work at a driving range doing the ball shaggin. mowing a range is a huge PITA unless they are closed one day of the week. there is ALWAYS someone out there smacking balls, you have to coordinate mowings with the ball shaggers to get 99% of the balls off the range otherwise you'd better run a grass catcher to catch them balls (which will then be ruined).
think about the PITA factor unless the guy is willing to close the range for an hour or two while you mow after he has shagged everything.
Efficiency = Profit