There is a right and a wrong way to execute self-revelation, and it largely has to do with subtlety. Being a physical event, the battle has to be overt. There can't be any second guessing over whether or not it's the climactic confrontation between the hero and the opponent. Part of the reason, I think, is because it needs to show the audience that they have in fact reached the climax of the story, but also, say, how many fistfights have you seen that are cloaked in subterfuge? Not many, huh?
The self-revelation is the polar opposite of the battle. It's fighting on an internal level within the protagonist and it has to be done quietly. If the hero comes out and announces what he's learned about himself, then he sounds preachy. You don't want to subject your audience to this. They're not in church. It has to be executed either visually in film or through non-dialogue prose in fiction.
Also, don't assume that all self-revelations must be positive. Yes, there are times when a character learns that he's behaved badly and needs to change his ways, like Scrooge in A Christmas Carol. But there are times when the character either doesn't recognize his flaw, or better yet recognizes it but is unable to remedy it.
Full Metal Jacket is filled with negative self-revelations. It's negative in Parris Island because, in spite of his training, Joker's passive nature prevents him from stopping Pyle from killing Hartman.
The self-revelation in the Vietnam half is a bit of a grey area. On one hand, you could say that it's positive because Joker comes to understand the severity of the war and finally makes the choice to become a fighter rather than a mere reporter. Then again, he's sacrificing his humanity from the first half. Stanley Kubrick solidified this visually. As Joker turns to shoot the sniper, the peace button on his vest is covered from view, leaving the audience to see "born to kill" on his helmet.