Because our water heater, if left on when traveling, "blows out", attempts to restart and then "locks out", we always turn the water heater OFF before traveling and turn it ON again when we stop for the night or set up camp.
However, when boondocking, (and when "overnighting"), we continually run our "propane only" 10 gal Suburban water heater and the Norcold refrigerator on propane, (and we use the LP cook top as needed)...
20 lbs, (4.7 gal), of propane lasts 3-4 months, if we don't need/use either the propane furnace or our LP Onan.
BTW, we always run the Norcold refrigerator on LP, (and when necessary, the Suburban furnace and/or the LP Onan), while traveling.
'96 Safari, 132k miles