I am not a breeeder but this is all so interesting to read. I am learning so much here.
I don't think multiple c-sections are any crueler than tail docking, or unnecessary s/n. Cruel is cutting a puppies tail off without anesthesia. I had one but I know woman who have had more than one. It wasn't that bad.
I think that because Irene uses an excellent reproductive specialist as a part of her breeding program, that she is getting good advice and doing what is right by her females. In the case of a breeder who wasn't using the very best vet for her breeding program, I would say that multiple c-sections may not be in the best interests of the female.
I know that there are a lot of ordinary general practice vets who do not know what they are doing with yorkies on a day to day basis much less a brood bitch. If I were a breeder, I would only use a vet who was a "specialist" in breeding or at the very least one who had a ton of experience with yorkies and yorkie breeders. There is too much risk with breeding yorkies not to use a reproductive specialist if one is close to you or, if there isn't close, then, MOVE closer to one, don't breed OR find a vet with lots of breeders as clients. I don't think cost should be a factor when making these decisions. JMHO.