Brake wear is a massive variable. opinion and types vary but usually a short haul airliner will see a brake unit change needed anywhere from a month to a year depending on use.
Carbon brakes wear at different rates to steel. Carbon brakes do not like being ridden on, i.e. trail braking continously or against power. The technique of rolling along at idle then applying once to bring speed down to walking pace before completely releasing in cycles is meant to help reduce wear or so we are told.
Sorry there is no definitive but brake wear is such a huge variable.