As far as I think ingress speeds need to be high...and this is the only parameter that affects the same...the reason I mention this is because I have noticed an increase in survival; what happens is an aircraft entering into an engagement at 300kts is out of energy once he makes his first evasion from SAM's and has gotten less farther away from the threat than one that was flying at a higher speed.
Might I add that this is with reference to WOI circa '79-though I am confident that the results would be the same in other environments as well.
Adjust to taste. I fly Eagles, Falcons and Phantom's mostly so I generally fly fast and low.
Besides, the AI do not run out of fuel.