@pedantiq If i remember correctly the limit is 4 members per team, but the majority of teams goes with 3 because it's easier to coordinate this way, Kitora's team has 4 total is an example, they are 3 gunner/fighters and 1 sniper, the team of the boy with super hearing has 3, all fighters ( forgot the name of this team, to much time without reading ).
The point is i think maybe the limit is 4, maybe 5 in real combat, in the end, they need to think of the teamwork, in this manga this aspect of the fights is really well done, even those specialized/super badass characters can lose if the enemy has a better teamwork even if they individually are weaker.