I suppose the Team Leader will be chosen at the beggining of each mission, depending on what kind of a mission it is and who's good what what.
I thought a fixed team leader is better for authority and all? If it changes with every mission I'm feeling like it could get chaotic or maybe even "you're not my boss" kind of attitude sometimes. Of course there's people of expertise in teams that know more about specific things than the leader might does, but the leader isnt supposed to know everything. They're supposed to organize and lead a group of people. Tell them what to do in what order and have a strategic mindset. They should be able to have a clear mind under sudden attack and form a defense strategy quickly if needed. They dont need to know all the specialties of the planet. They just coordinate the group and knows how people work together and who to put to what exercise to have the best results.
I know that Jessa for one wouldn't make a leader. And that she would even refuse to be. And she would also refuse to listen to someone who has no experience, education or knowledge in how to make a bunch of people funtion as a team.