How much data should my Service Worker put upfront in the offline cache?

Nicolas Hoizey analyzes why it’s not a good idea to just hook up Service Workers and save all resources offline. Given the fact that a lot of users might never come back or that they simply won’t read through all the pages of a website, downloading megabytes of data on first load might be a very bad practice — especially when we keep data plan costs in mind. Looking at these numbers, the 3MB of an average web page are nearly negligible if a Service Worker loads 16MB of useless data on initial page load without further ado.