Do people work better creatively when teamed up, or does the danger of groupthink lurk?

Yes, to both of them.

It's like asking a question that would an athlete become better with training ? or the danger of injury lurk?

Just like the analogy above, Both the increasing productivity and the chance of group think are inseparable from one another because unifying mind and goals often needed in both of them.

Ibelieve b) recall election