I leave both my RV's refrigerators running all summer.
My 5th wheel refreg is turned on from March-November. My brother and I have our own private campground. The electric bill goes up about $1 per day per RV when plugged in with refreg on electric. (not including AC usage when occupied).
The Wolf Creek runs on propane all summer since it never gets plugged in unless in a campground. Since I was full of propane in late May, now I know a tank is good for just over 1 month. (a tank fill cost $6.00 where I live).
This tells me propane is more efficient for refrigerator than electric.
I don't unload the Wolf Creek until Thanksgiving. so when I use the truck to shuttle back and forth between home and 5er I can also carry food in WC refreg, I also have the WC fresh water tank setup so I can suck water out of it and into the 5er (no water on site at 5er location). Plus I tow my motorcycle trailer behind truck (which also has a 35 gallon water tank on-board).
I truly believe the refrigerators last longer when used like I do. The Amish neighbors use the same style system for refrigeration, and the don't have the system failures like the RV world does. But I have no data to back this up.