Teamwork as a whole can naturally produce an overall greater productivity through the concept of synergy , where the total of the whole is greater than the sum of its individual parts. But the idea that people work more productively in teams rather than as individuals is going to vary greatly between the types of teams that are organized, the end reward or motivation for both the team and the individuals, as well as the individuals themselves.
Regarding individuals, some people are born with the desire to succeed, no matter what the situation or task that they are facing. These people may evolve into the classic Type A personalities that work ferociously because they are driven by an internal fire that says they must always be doing something, whether individually or as part of a team. Other people may desire to be less socially involved or are very highly competitive with other people. For these people, their work is most productive as individuals, because the very idea of cooperating with other people limits their effectiveness and efficiency because they simply do not want to be a part of the team. Whether this mindset is innate or developed over time does not matter, it is merely the state of their being and neither motivation nor rewards can generate inside them the desire to work collectively as a team.