Pareto principle

The Pareto principle (or the 80-20 rule), states that 80% of the value of something is comes only 20% of the effort. Conversely, the remaining 20% of the value is comes from the 80% of the work. The implication is that in situations where perfection is not needed, it is better to only do the 20% of the work that gives the 80% value.

Of course, in the areas where the Pareto principle holds true, it is only possible to use effectively if it can be determined what 20% of the work that provides the largest value.