I have found keeping mine running all the time works best. We keep a bunch of bottled water in there so its not completely empty. If you want to turn it off, you can do so by raising the temperature setting until it turns off.
Not sure if this has anything to do with it but I turned mine off over the winter from December until late March. Then on that first trip, the compressor started going bad. It had to be replaced but fortunately, under warranty. Now mine runs 24/7/365 just like the unit in our house.
If you decide to leave it running, maybe raise the temp setting just a little so it doesn't run as much.