Fridge usage in class B

We plug it in 24 hours before departure and load it just before we drive off. Turn it off again when we unload upon return. We do a lot of 3-4 day weekenders at the moment.

If I had the RT in the driveway, I'd fire it up a couple days before a trip, not just to pre-chill it, but in case there is an issue, you can possibly get it fixed before you have to head out with a dead fridge. There are many full-timers using these fridges 24/7/365.25, and because the only moving part is the liquid, it can't hurt to keep it going. My preference is to run it on propane, but one can go either way.

Of course, this is assuming the fridge is on a level stretch. RV absorption fridges will self destruct (and the damage is cumulative) if left on and out of plumb for any real length of time.

We use our van about every weekend. I generally run the fridge on gas and turn it on when we get going. I put stuff in the freezer as that gets cold pretty fast. Then I move it down once the fridge cools off. If I'm bringing a lot of stuff, I cool it down the day before. I think it is better to use it than not - particularly the gas feature. You do not want things building up in the piping - such as spider webs.

You can do it either way provided you store the RV in a spot that is level when not in use. I don't know of any real "downside" of either method since there are no moving parts in the fridge. I've had some RVs that the fridge ran all during the summer and others that I turn off and on only when needed. My CURRENT fridge I turn off when not in use and the reason is that it takes only about four hours to get completely cold. Some models can take as much as 24 hours and that would be a good argument for leaving them run (if you tend to be a bit spontaneous as I have been). Never wanted to delay a trip while waiting for the fridge to cool :)

I turn it on a day or so before I'm planning to leave. Unless you are planning to leave food in the fridge, I'm not sure why you would want to leave it on all the time. I don't think there is a negative impact by turning it on and off.

Our normal routine. 48 hours before we leave refer on. 24 hours before load food. Day of, depart.
But we also leave our trailer plugged in 24/7 at home.