No, a breeder can't figure that our from 8 week olds. Most good breeders wouldn't breed a bitch in the following heat cycle after a pregnancy anyways. Another question is, does the breeder own the sire and the dam? If they do, it almost sounds like they're just giving an excuse for breeding their two pets together over and over.
Most breeders that repeat, do it after seeing the dogs develop to about a year old, get shown/trialed/trained, and get a lot of comments from people that aren't the owners of the pups that the litter was solid.
I guess I'd like more information on why you consider this person to be a good breeder...there are only a few situations which I know of where a good/reputable breeder decides to do a repeat breeding. They generally aren't smart for the future of the program because if you truly believed that the litter was so good, then you probably would've held one of the puppies back and not needed to do a repeat. Also...if the genetics are so good, wouldn't it be smarter to improve upon that last litter by mixing in something good as well? Not just repeat the same thing you did last time?