1 + 1 = 3
Two people who collaborate well will be about three times as effective as each of them operating independently, because each will see what the other might miss—plus they can leverage each other’s strengths while holding each other accountable to higher standards.
3 to 5 is more than 20.
Three to five smart, conceptual people seeking the right answers in an open-minded way will generally lead to the best answers. It may be tempting to convene a larger group, but having too many people collaborate is counterproductive even if the members of the larger group are smart and talented.