One of the many interesting stories from They Made America: Two Centuries of Innovators from the Steam Engine to the Search Engine, by Sir Harold Evans is the story of Samuel Insull. His innovation was in pricing. He worked on understanding how his customers would use electricity, and then devised a pricing method to meet the estimated need. A key part of his understanding was that he saw the peeks and valleys in the usage chart between the very different customer populations. His insight came to him because he looked at the entire system of generating and using electricity.