I took my 2001 Jeep Cherokee to the dealer recently for a 60,000-mile check-up. There was the standard package of items-brakes and coolant checked, engine inspected, basic stuff. The car was delivered to the shop and I waited for the inevitable call that would tell me that some things needed doing that I had not anticipated. Some of this work was safety related-worn brake pads and the like. I said fine, do it. However, I did not okay work falling into the category of potential problems downstream. I measured the risk, cost, and how long I would continue to operate that Jeep (my reputation is that I keep cars forever) and made the decision that the rest of the work could be deferred to a future date, hopefully a very distant future date.
This is not unlike what occurs when we repair ships here at BAE Systems Ship Repair. Ships, like cars, require maintenance check-ups and repairs, but on a schedule based on time, not (nautical) miles traveled. As with cars, there is a package of work planned in advance. And, yes . . . there are the phone calls.