It depends on how you drive. There are people that drive wide open, tailgate and use the brakes a lot to slow and stop. There are others that are more aware of their surroundings, maintain proper distances and don't use their brakes much at all. We had one truck driver that would get 200,000 miles on a set of brakes on a 62,000 lb GVW roll off container truck. The average driver would get 100,000 miles. We had one who would only get 60,000 and another that got 40,000. They all drove the same trucks the same places putting on 100,000 miles a year on average.
We also had trailers that contract drivers would pull and some of them would wear out a set of trailer brakes in 30,000 miles. We suspected they were using the trailer brakes instead of their tractor/truck brakes.