Pads have to be thoroughly inspected.... with the rims off preferably. Not just a quick peak through the rims. There is always a chance that just one pad is wearing unevenly on one side and cause issues if not replaced on a timely basis. I just had my brakes inspected with 20,000 miles on new OEM pads and OEM rotors front and back. I do all city driving with loads of speed bumps. All pads were at 50%. I will most probably change all my pads before an additional 10,000 miles while checking them at my next oil change. I don’t mess around with my brakes or tires. I’d rather throw away some money when there is still sufficient pad or in the case of tires, tread left. I just feel better with a lot of meat on my pads and tires. Peace of mind fior those “emergency stops” and torrential downpours.