One of many things Amazon is famous for its two pizza rule. The rule simply states that every internal team should be small enough that it could be fed by two pizzas.
It’s unclear whether Amazon adjusts for the specific appetites of the team members involved, but the broader point is clear. This rule is all about efficiency. Smaller teams move faster; they spend less time on administration and oversight, and more time executing.
The natural converse of this rule is that if you want to slow a team down and derail a project, one surefire way to do it is to add more people.
And, if you really want to create a mess, don’t clarify anyone’s role or assign overlapping responsibilities. If you’re heading down this path, you may want to skip the pizza entirely and just bring popcorn instead.