My experience is that the team is better off focusing on a smaller number of missions and being able to complete them (always depending on robot performance, of course) - rather than trying to do a large number and being only partly done with each one so there's no chance of success at the robot game. It's really exciting for the team if "what we learn" includes the knowledge that they can create a robot and program that actually accomplishes something. It's not about chasing a high score - more about showing themselves they can reach a goal.