Out of curiosity, I have heard the term used as a "rule" for the value of a gift. How exactly would that work (not planning to implement but just understand) when the couple is not giving guests a bill like at a restaurant, nor sharing details of how much vendors cost? How does the guest know that the couple isn't on a budget or thinking outside the box as part of their personalities? Wouldn't it it just be easier to say "ok I'm willing to spend $x because they are my best friends (or not that close) so what on their registry that they want is in that price range?" Otherwise it sounds like too much math and trying to one up each other?