You're right about the pairing of the fighters in the CAP action. You're also right that they USUALLY attack in pairs.
However, I've seen them attack with the entire flight. My guess is that its based on the number of incoming bandits, but ...? The same with one pair following quickly after the first attacking pair. Is there some code that checks the number of incoming bandits?
Also, please note my comments on CAP action under Recluse's post. Do you have any comments about that?