I think I have it all figured out.. what I've been trying to do - unsuccessfully - is to get the fighter sweep flight to break off on two possibilities:
1. they're out of ammo
2. I've hit the target and heading home
Individually, these are easily set up, but getting both of them to work hasn't been possible. The end result is that if I set them up to break on ammo depleted they don't leave if there are too few bandits (variable percentages) and get shot down coz they stayed around the target area too long.
On the other hand, if I set them to break when I destroy the target they stay in the air even if they engage a gazillion bandits and fire a gazillion missiles - not very realistic.
The obvious solution seems to be to spend countless hours refining their courses and the bandit appearance percentages - something I'm trying to avoid LOL.