I started using Griot's Garage 3 in 1 Ceramic Wax last year on my daily driver that gets parked outside in rainy Washington state. The wax on the lower half of the doors that catch water spray off the tires started weakening at around 6-7 months, while the wax on the rest of the paint was still going strong up to 10 months. I only washed the vehicle a few times throughout the full 10 month period by spraying it off with the wand at a self service car wash, so I might have gotten a full year if I did more maintenance in between.