How Does the 80-20 Rule Apply to Presentations?

In the late 1800s, Italian economist Vilfredo Pareto observed that 20 percent of the peapods in his garden yielded 80 percent of the peas. He also noted that 80 percent of the land in Italy was owned by 20 percent of the population. So was born the “Pareto Principle,” sometimes called as the “80-20 rule”. [...]