I guess it turns into a cost benefit analysis where you have to compare maintenance to demolition and land value. Beyond a certain point that estimate would become less predictable. But the design will have margins of safety that increase predictability. A client buying a bridge or a skyscraper will probably be making a long term investment and want predictability.
That’s fascinating. I wonder how they interpret “minimum”. Do they try to just cross that threshold or overshoot by a lot?