Once your team learns to cheer each on and rely on each other in short bursts, it goes a long way to soothing problems that can arise in the rest of the season- robotic design disputes, skit role issues, and other personality conflicts.  It won't cure all ails, but it certainly improves a team cohesion:) 
   Make sure you stress good communication models in the instant challenges. A way to introduce more ideas is to say that, "That's one idea. I have another."  "We could also...."  "Kinda of like that idea, .... " The goal is non-judgement of stated ideas, while still forwarding the new idea.  If kids judge ideas or put ideas down, stop them and remind them that the brainstorming part of open to all ideas. They should even try to refrain from making positive remarks, because that can seem like an endorsement for one concept and stops other people from forwarding different ideas if they don't think the new idea has any chance.  I found my teams were enriched by the exercises, and it made the meetings so much fun to have them each time we met.