The other thing is with a lot of small fighter Groups you can effectivly block a large portion of your fighters out of range of the targets. But since the targets weapons are not as short of range as the fighters, this isn't a problem for them.
Although Mephisto before your post I was sure that large Groups were the way to go and I am not now. Perhaps the positives/neagatives to both methods balance out and it doesn't really matter.
Geoschmo