This is more like the 70-20-10 rule -- not so much numbers that you've calculated based on careful observation of any particular business, but rather a nice set

This is more like the 70-20-10 rule -- not so much numbers that you've calculated based on careful observation of any particular business, but rather a nice set of round numbers to aim for. I've heard of this rule before, although when I heard it it was the "45% rule". Close enough.