Question about propane water heater?

We are in a small travel trailer so it is gas only. It is a little noisy as you can hear the flame burning from a distance but not as bad as an AC unit or generator.

I was mainly thinking for safety (as in leaving the unit on for the day while were gone) or propane preservation. Wasn't aware there were safety switches on the units and that they needed very little propane.

All great info.

Thanks!