The timeless 80/20 rule. 20 percent of the people do 80 percent of the work.
It is timeless and it is versatile. It shows up everywhere. 20% of the people make 80% of the money, etc. Just recently I was wondering if anyone remembered that or if it had faded away. I think it is especially informative when thinking about redistribution of wealth. If we started over with everyone having exactly the same amount of wealth it would not be long until the 80-20 rule had once again redistributed the wealth.