Overprovisioning to ensure demand is met in the worst case also sounds like a very early-20th-century sort of design decision; that could be part of it!

Here's an interesting article about Spanish flu and radiators: https://www.bloomberg.com/news/articles/2014-02-17/our-indis...

"engineering manuals from the 1920s dictated that radiators and boilers be manufactured large enough for 'the coldest day of the year, with the wind blowing, and the windows open.'" (!)