Rule 20-80

Rule 20-80 states:

1. 20% people have 80% wealth.
2. 20% of your customers generate 80% revenue.
3. 20% of your employees complete 80% of their assignments.
4. 20% of your reading is enough to provide 80% knowledge.
5. 20% of your effort generates 80% of your expected outcome.
6. 20% of a software fulfills 80% of your requirements.
7. and so on ...
   

The rest 80% usually gives you only 20% and can be ignored if you love free time and higher productivity. The trick is to identify the 20%.