Cold weather? I realize that many campers have no choice and have to stay in a cold environment because of family, work or other local resources, but we are lucky that we can camp where it's unlikely to freeze. In our case, if we are camping where there's a threat our hose may freeze, something has gone seriously wrong. I hope if we are ever in that situation, I will heed your advice and unhook from the city water.
In our case, we have two adults and two children on board who like to take showers. Furthermore, they also like to change clothes a lot and that means we have to run the washing machine at least every other day. Add in the dishwasher and we probably average about 120 gallons of water per day. So it would not be practical to unhook or even turn off the city water at the faucet. In fact, we even leave the gray tank valve open at all times to drain the gray tank or I'd be out there once or twice a day emptying the tanks.
So it really depends on the situation. Sounds like you've found a good solution for your situation. When the kids move out and we find ourselves camping in the cold, I hope we'll remember this post.
