Problem solving in a team can be really powerful. You split up the work to save time by working in parallel. You can discuss data, findings, and ideas with your team tapping into a collective brain that is bigger than yours.
I find that designing presentations though is best done by one person who has the pen. One style, one approach, one story flow, everything gets said once, everything that should be said gets included. Multiple captains on a ship create an inconsistent story.
That is also the reason that I am not a big believer in realtime office document collaboration, a feature that many software publishers try to implement. The fact that the Internet makes it possible does not mean that it is a good thing.
Team input is important, but only one person should have the pen to incorporate them into the story.