Founder team size has two contradictory effects on effort:
- The larger a team is, the more social loafing occurs: each founder has a greater incentive to "free ride" on a larger team and withhold effort. This causes each founder to put in less effort in a larger team.
- The larger a team is, the more peer pressure there is to contribute effort. As the extreme low end, in the case of a sole founder, there is no co-founder peer pressure at all.
Having the hours worked peak at three founders can be unfortunate in that larger teams require spending more time on communication and coordination activities. In my opinion, larger teams should consider making an explicit effort to work more, rather than fewer, hours than three-founder teams, for example by agreeing from the outset on aggressive work-schedule expectations. This would compensate for the additional coordination overhead. This assumes that the coordination activities can be managed in a way that doesn't greatly increase mental fatigue, which I believe is a reasonable assumption.