80 20 Principle - vital few, trivial many

What It Means

The 80/20 Rule means that in anything a few (20 percent) are vital and many (80 percent) are trivial. In Pareto's case it meant 20 percent of
the people owned 80 percent of the wealth. In Juran's initial work he
identified 20 percent of the defects causing 80 percent of the problems.
Project Managers know that 20 percent of the work (the first 10 percent and the last 10 percent) consume 80 percent of your time and resources. You can apply the 80/20 Rule to almost anything, from the science of management to the physical world.

You know 20 percent of your stock takes up 80 percent of your warehouse space and that 80 percent of your stock comes from 20 percent of your suppliers. Also 80 percent of your sales will come from 20 percent of your sales staff. 20 percent of your staff will cause 80 percent of your problems, but another 20 percent of your staff will provide 80 percent of your production. It works both ways.

How It Can Help You

The value of the Pareto Principle for a manager is that it reminds you
to focus on the 20 percent that matters. Of the things you do during
your day, only 20 percent really matter. Those 20 percent produce 80
percent of your results. Identify and focus on those things. When the
fire drills of the day begin to sap your time, remind yourself of the 20
percent you need to focus on. If something in the schedule has to slip, if something isn't going to get done, make sure it's not part of that 20 percent.

The 80/20 Rule, should serve as a daily reminder to focus 80 percent of
your time and energy on the 20 percent of you work that is really
important. Don't just "work smart", work smart on the right things.