How often should brakes be changed?

If you're talking front ones, and they were installed properly and the system doesn't develop other problems to cause premature wear, and also depending if you're talking city or highway driving, not to mention what quality of parts were installed, I would expect about 35,000. If you have rear drum brakes and you keep them adjusted every 12,000 miles your fronts may last longer. If we are talking rear shoes I would expect 75,000 miles, rear disc brakes about 50,000 miles