I'd say luck has a major part to play in fridge life. Here are a few of my observations to help with fridge life:
1: Keep it level. This is the biggest killer of absorption fridges. Damage is cumulative.
2: This isn't really for fridge life, but to get to operating temperature. Since I use my travel trailer on weekends, I turn my fridge off. When bringing food, I stuff an ice pack in the freezer, and one in the refrigerator part (where the small, Valterra fan blows on it.) This gets both compartments to an operating temperature.
3: If the fridge is not in use, and you are not on the road, keep the fridge doors ajar, either by the airing positioning cards if a Dometic fridge, or via the latch if Norcold.
4: Every few months, checking the flame area and cleaning the flue (spiders love that area) is wise. Mud dauber wasps love the fridge area, so it isn't unwise to consider screens.