Someones opinion isnt a scientific study no matter what their experience or qualifications. If experts use words like "can, might, feel, may" etc we can;t interpret those as "always, do, " etc. the uncertainty needs to be respected far more than any implication of certainty.
Sceintific studies are peer reviewed before becoming accepted scientific theory.
Someone isnt right becasue they are a breeder of many years and feel a certain way but I agree their experience can't simply be dismissed out of hand.
Some more to mull over.. paras 13,14
Puppy Socialisation and Habituation (Part 1) Why is it Necessary?
David Appleby
Puppy Socialisation and Habituation (Part 1) Why is it Necessary? | Association of Pet Behaviour Counsellors
"What practical applications do we have that bear out the research? Guide Dogs for the Blind, who, until 1956, used to rely on the donation of adult dogs which they took on approval to maintain their training stock. The success rate of these dogs fluctuated between 9 and 11 percent and it was recognised that this could be improved if the association could supervise the rearing of puppies. These were purchased and placed in private homes at between ten and twelve weeks old or even later. Things improved, but the results were not good enough. It was Derek Freeman, who pushed to have puppies placed in private homes at an earlier age to optimise socialisation and habituation during the critical development period. Derek had a strong belief in Scott and Fuller’s work and importance of early socialisation and habituation in the production of dogs that were best able to survive and perform in the world at large.
Derek found that six weeks was the best time to place puppies in private homes; any later critically reduced the time left before the puppies reached twelve weeks; but if puppies were removed from their dam and litter mates before six weeks they missed the opportunity to be properly socialised with their own kind, which resulted in inept interactions with other dogs in later life. The training success rate soared because of this policy, which was carried out in conjunction with the management of the gene pool via the breeding scheme Derek also pioneered. Annual success rates in excess of 75 percent became common. You might think that this is a special scheme for dogs with a special function. In fact, what the scheme provides is adult dogs with sound temperaments. These dogs coincidentally make the best material for guide dog training which does not start until they have been assessed at ten months or older. As a result of the breeding scheme, Derek Freeman also proved, if proof was needed, that you cannot dismiss the importance of genetic predisposition, i.e. the basic material required for good temperament can be produced through good breeding. Conversely, a lack of habituation/socialisation can ruin the chance of an individual developing a sound temperament, however good the genealogy."
and
"Having said that, it is unfortunate that some breeders believe that most families are unsuitable to look after a puppy when it is six weeks old, although it is difficult to see what suddenly makes a family suitable when the puppy is eight, ten or twelve weeks old. All too often breeders, unaware of the harm they are doing, retain puppies well into and sometimes past the critical socialisation and habituation period so that they, the breeders, have time to choose which puppy or puppies they wish to keep for showing before launching the rest on the unsuspecting public. There is in essence nothing wrong in the breeder retaining a puppy for as long as they want, as long as they systematically ensure that each puppy is properly socialised and habituated as an individual. Each puppy needs to learn to cope with the environment without the support of its litter brothers and sisters and other dogs. Although this is possible, in practice, it is very time-consuming."