In 2012 my wife was pregnant and had complications mid camping season that brought a quick halt to our camping. After the successful (and HEALTHY!!!) birth of our daughter, we took it out for some late fall camping. We neglected to drain the water heater and the bacteria in the water from our last trip had made a horrible sulfur smell in our tank.
Since then, we drain EVERY trip. Its really pretty easy, after I turn off the water we open the low point drains and open the faucets. Water drains while we drive home. When we get home and clean out food and pillows, I close the low point drains, knowing there isn't any water left in the camper.