When asked to design a style guide for the digital brand as well as David Yurman's sales partners (Neiman Marcus, Bloomingdale's, etc.), I noticed the in-house print designers always used the Rule-of-Thirds when laying out the David Yurman billboards and magazine ads. The Rule-of-Thirds is a good approximation of the Golden Ratio and is a lot easier to do the math for, so I based all the design guidelines around this principle. The font sizes, the leading and the spacing are all multiples of 3. This system was so easy to memorize and execute that I still use it til this day (including for this website) and even taught it in my college UX classes.