No need to argue over this one, as the best solution is for the original poster figure out a way to mower more often. None of us can see the slope that's being cut, the material that's being cut, or how the operator has been cutting in the past. Half acre shouldn't take that long, unless it has obstacles, or the slope is severe. I've said as much as I can, but we all know that as a mechanic, my opinion isn't worth much and we are talking about a landscaping problem.