I winterize/drain approximately 225 houses each Fall. I also winterize a dozen or so lawn sprinkler systems. I tow a 4 cylinder diesel air compressor behind my work van and hook on to the main water line that feeds the sprinkler system. All of the sprinkler systems in our area of Rain Bird systems. There is a setting labeled "test all valves". It opens each zone for 2 minutes while I apply a lot of air volume, not just pressure. I go through the cycle three times. In ten years, I've never had a sprinkler system freeze and break, and it gets down to -15 degrees F here. I'd say it is fool proof if it is done correctly. I can blow out a 10 zone system, including travel time in about 1.5 hours. Fairly inexpensive to the average homeowner that afford a 10 zone system.