Even if you design a component to last for the life of the entire system, that doesn't mean there's no point checking it through that life. There will always be

Even if you design a component to last for the life of the entire system, that doesn't mean there's no point checking it through that life. There will always be the pieces at the bottom end of the bell curve. You must catch them. Look at the aviation industry for a good example. A pilot might check certain parts of the aircraft before starting it up each time. They'll likely check more things more closely for their first flight of the day. Then it'll get ever closer inspections every X days by maintenance personnel. These checks catch faults.