I bought my car new in 2007 and now have 90,000 miles on it. I can‘t ever remember having the brakes serviced or pads changed.
It entirely depends on how you drive. I did deliveries for a long time, Pizza, Chinese, Flowers. I would go through two sets of pads a year. In fact, I had a little side business doing brakes for my co-workers My sister has a 2002 hyundai accent with 150k miles she bought brand new. She just last year had the pads changed for the first time, and they had half the meat left on them. But she drives like a scared little old lady. She's the one you get stuck behind, blowing your horn. They start off about 3/8 inch thick. When they get to somewhere between 1/8 and 1/16, change them.
All cars are different. But the pads you replace them with makes a difference too. If you buy the ones that last longer, they are made of harder stuff and will wear the rotors down quicker than ones that lasts less mileage. you want to replace the pads from wear, not the rotors. I always buy the mid range replacement pads. They last better than the cheaper ones, and don't wear out my rotors like the high mileage, higher priced ones.
Until they wear out. Depends on alot of factors. Brake pads may be ablative or abrasive (metallic, semi-metallic, ceramic). There's also organic brakes, but i have no idea if they are abrasive or ablative. Pads that are abrasive have shorter life spans, but are less susceptible to heat distortion or damage from heat. Pads that are ablative have longer life spans, but are more prone to heat distortion or glazing, or other types of heat related damage. Then there are other factors, such as driving style, weight of vehicle, etc. If the car is subject to rather spirited driving, then the brakes tend to not last as long. Also the condition of the brake system makes a difference. The pads in a system that is sticking or binding (causing the brakes to be constantly applied) will not last as long as those in a system whose calipers move freely. Also, the same model vehicle may have different design brakes, depends on options they may be larger, or of a different type. An example that comes to mind are older F-Body cars, the 6 cylinder types had rear brake drums, while the 8 cylinder models had all wheel brake pads. I'm not trying to be a jerk, but I don't think that anyone can give a mileage as how often brake pads must be changed, or how long they will last. The answer to your question is, they last until they are worn out.
