If the game closes after submitting the score, it will automatically exit full screen.
If the game keeps running after submitting a score, it has no way to signal to the screen that it should exit full screen, especially because you might be able to start a new scoring session within the currently active game.
Theres no way to control which method a game implements, though most ibpro/v3 games are the former, and most mochi are the latter.