CainIV - 5:49 am on Oct 24, 2011 (gmt 0)
In my opinion 80/20 describes building systems thinking. 90+/10 describes systems perfection. Both are two different entities in the lifestyle of a business.
In order to grow from an adolescent business to a mature business, a business must usually undergo a period of 80/20 thinking. This allows elements to be build out at a rapid enough pace to allow the business to leverage systems thinking and move up revenue levels.