This was purely an informal poll. Breeders of 6 different AKC breeds replied. Those breeds included Dobermans, Boxers, GSD's, Corsi, Pomeranian's and French Bull Dogs.
Here are the results:
Reputable breeders return money to buyers if there is a health issue with the puppy then if this is a returning issue of more than one puppy spay the bitch, test their lines and take appropriate measures to insure this does not happen again.
Reputable breeders have 1 - 3 litters per year and breed to improve the breed not to sell puppies and make money.
Reputable breeders of large breeds only allow their bitches to have 3 litters and smaller breeds allow their bitches to have 3-4 litters.
The average age of a bitch when producing her first litter is 2-3 years old and done after she has her health testing and hips.
The average age of a male when producing his first litter is 2 years old and done after he has his health testing and hips.
And finally if you have more than 6 litters a year consistently you are considered a "PUPPY MILL" by reputable AKC breeders.