To each his own but we keep ours on and what a pain if we need hot water and forgot to flip the switch. We put in on electric as we have already paid for it and it does not cost anyone much to maintain it to be hot. Before showers on most days we turn on the gas for a quicker turn around and then hopefully remember to turn the gas off but sometimes we forget.
I like hot water all day to do dishes and wash up after using the bathroom or doing something around the site.
Ever need hot water in a hurry, yes. Camping in October, 30 degrees out at night, pitch dark. Neighbor just starting a fire and we were clearing the leaves around the firepit. Who knew the river was 5 feet from his firepit. Down I went totally underwater to the bottom of the river. Crawled up the bank of the river, slightly wet, lol, very cold and bleeding. Thank goodness the hot water was on. I was stripped of all clothes by the time I hit the trailer door and went right into the shower. A nice hot shower saved the weekend. If the heater was not on I am not sure what I would have done.