In the world of scifi/horror, it's almost a "given" that the characters do stupid or irrational things. This show takes it to a whole new level, though, and became unwatchable me for when the French woman scientist waited until half the army squad she was with was wiped out before deploying a weapon she had developed to thwart the aliens. Having already endured multiple instances of people wandering away from their group and getting killed, people leaving their only weapons laying around, and soldiers walking in the open without cover while in well known danger, it was just too much. Even under extreme stress, people don't behave that way.