One place where I can still see this working well is landing pages for marketing campaigns; it’s a fair assumption that most visitors there will be first time v

One place where I can still see this working well is landing pages for marketing campaigns; it’s a fair assumption that most visitors there will be first time visitors. Other than that, I’d say that there should be a mechanism where the browser informs the server of what assets they have cached, although I can only assume that may open a privacy can of worms.