And someone can do lots of training simulations, pass with flying colors, and still choke when confronted with the real deal. Remember Lt. Gorman in Aliens?
Why is this his first “real deal”? Shouldn’t he have seen this kind of action many times before ending up in Ren’s unit? I mean Ren knew his serial number off the top of his head. He was obviously informed about the troops around him.
As a viewer, I really shouldn’t have to read the novelization to make sense of the characters’ motivations.
Why can’t it be his first taste of combat action? When was it established that he was in some sort of elite and experienced stormtrooper unit and only the best of the best ever went into battle with Ren? If stormtroopers are commonly used as cannon fodder wouldn’t they constantly be bringing in some new reinforcements anyways? I don’t think Finn’s behavior really requires any more of an explanation other than what they show and what he tells us in the film.