> To be sure, it’s not always exactly 80/20. Sometimes it’s 90/10. Sometimes it’s 70/30. Note that the numbers do not need to add up to 100. Sometimes it's 50/

> To be sure, it’s not always exactly 80/20. Sometimes it’s 90/10. Sometimes it’s 70/30. Note that the numbers do not need to add up to 100. Sometimes it's 50/50, 60/50, 95/90, π/e, ... Sometimes you have no choice to go 100%, for example if you want to reach the summit of a mountain. It then makes no practical difference when you reached 80% of the height in 20% of the time (or whatever). To make use of the Pareto Principle, and I do it a lot, means to permanently re-evaluate one's to-do list and switch task when someting else seems more promissing. This still leaves many questions open, such as: "Promissing in the short or the long run?", etc. Applying the principle is an art not a science.