"Okay, here is where I think a lot of people lose a lot of money, worrying about things they can do nothing about. These dogs PASSED CERF once, why would you do it again and again in the future? Especially at 5 and 6 years of age when the dog has most likely been bred multiple times? At that point, you aren't going to be able to change anything. Even if your dog passes all the CERF's, he/she could still throw pups with eye issues.
I feel it is a great pull from Eye vets to get as much money as possible out of breeders........."
Here is why you should do multiple CERF's. Friend of mine bought a pup who was to become her future stud dog. At a young age-under 6 months- he was CERF'd clear. Owner tends to breed on Preliminary hip and elbow reports from OFA, and he was used as a stud at 11 months of age and again at 16 months. Just before being bred a third and fourth time, co-owner of said females told stud owner to get the dog CERF'd again before breeding to these two females. She did and the results were severe Juvenile Cataracts in both eyes, failed CERF, NOT recommended for using as a stud dog. This is before the dog even turned two yrs old, and had sired two litters.
Did getting the re-CERF change the fact that he sired two litters? NO. Nothing can be done at this point to change that fact. However, it DID prevent producing more pups with future litters. Which is the whole point in doing CERF exams at multiple times to catch those diseases that tend to not show up until certain points in a dogs life.
As to the frequency that the female is being bred in the OP, I don't know the dog or the conditions of the dog or her living conditions. Maybe they plan on breeding three in a row and then spay? so that she can have the pups while relatively young and healthy and then enjoy "retirement" and training.