It all boils down to routine maintenance. No such thing as do it once then good for all time. Sad fact of it is the stone needs to be removed, cleaned and re installed at least every year, and depending on the rainfall, more often. In an ideal world, the stone grows over with low vegetation that stays in place during rian events, but never grows so thick so as to impede water flow. The only alternatives to this would be concrete, asphalt or better drainage(more culverts). No one ditch can handle all the water for the length of the road.