Hey it's your water heater.......use it like you want to.
Leave it on......turn it on when you want hot water (well at least 15 mins before you want hot water)
There is no only one right way to use it.
We have ours on always.......LP when no electric or on electric when we have power.
I hate cold showers......and when I want to take a shower I don't want to wait for the water to get hot.
The RV is our home...so I use everything in it just like I did in a S&B house.
Fridge is on, water heater is on, A/C-furnace set to come on as needed, water is on....and I use toilet paper that I like