The Pareto Principle.

The Pareto Principle is very simple, yet very important. It is named after Italian economist Vilfredo Pareto, who, in 1906, found that 80% of the land in Italy was owned by 20% of the population.

What was most important about Pareto’s finding was that this 80/20 distribution occurs extremely frequently. For example, in general, 20% of your customers represent 80% of your sales. And 20% of your time produces 80% of your results. And so on.

https://www.forbes.com/pareto-principle-how-to-use-it-to-dramatically-grow-your-business/?sh=766b543b3901&fbclid=IwAR1JPp8bmwus4ZyHRAv6OP2U4luaeTAKWhZFJ0n0IEWymeiHj11eCcdoBjI