20% of team members can communicate 80% of problem definition, solutions
80% of team members can only communicate effectively 20% of the time
20% of the volume of communications (meetings, emails, docs) communicates properly 80% content. 80% of the meetings are redundant.
80% of the money spent on a project has 20% ROI.
80% of comments read by HN users are only interesting to 20% of the users who read them.
20% of beer drinkers consume 80% of beer drunk
20% of people snoozes 80% of alarms
80% of Pareto Principle jokes are amusing only 20% of the time
The thing with Pareto is that it always sounds right, no matter if it's true.
Some interesting comments about the 1% rule and HN: https://news.ycombinator.com/item?id=9219581
As you get more data points, your generalization fails more and more often, and some failures are severe, adding more planning risk than everything else added.
Or, in other words, the rule works most of the time. And you can rely on it at all.