Why a small group can carry so much of the work
The “10%” rule is a shortcut based on the square root of a group’s size: in a 100-person company, the square root is 10. It suggests that a small core may account for roughly half of the group’s output. It is a rule of thumb, not a measured law that applies to every workplace.
One reason work can cluster this way is that contribution builds on itself. Experienced employees may solve difficult problems faster, know whom to ask, or take on tasks that unblock several colleagues. Their results make them the obvious people to turn to again, concentrating more consequential work in the same hands.
Why the pattern is hard to measure
“Half the work” depends on what counts. A completed sale or repaired system is easy to see; mentoring, preventing mistakes, and keeping routine operations running are harder to assign to one person. A few visible deliverables can make a team’s contribution look more concentrated than it is.
That distinction matters for managers. If the same people repeatedly absorb urgent or high-impact assignments, they can become bottlenecks—and risk exhaustion—while others get fewer chances to build skills. The useful takeaway is not to expect exactly ten people to do half the work, but to look for where expertise and responsibility are accumulating, and whether the team can still function when those key people are unavailable.
