Breeders belonging to clubs also have their animals tested in accordance with club regulations or even beyond. Genetic tests, for example, are already mandatory for all common clubs. Unfortunately, these tests and examinations often do not say much about the actual health and longevity of the animals. Animals can still get many diseases, even if a test result was negative, because either only 3 out of 7 alleles were assessed in the genetic test (as with HCM) or the disease only develops after the snapshot of the test, or the animal falls ill with something that cannot be tested for in advance (such as FORL, cancer or intestinal obstruction).
In my experience, most breeders do the health tests on their animals because other breeders do the same, but do not question the reason for the many tests on pedigree cats and their usefulness. For them, breeding only means reinforcing external characteristics that they like in the animal through breeding. They rely on an "experienced breeder" who teaches them how line breeding works and are happy when the cheap inbreeding in the direct line of the paper pedigree, on which only 5 generations are shown, does not appear. Half of the breeders I have spoken to over the years have never heard of a pedigree database like pawpeds and over 90% don't know what a coi is. They prefer to let their champion have 50 litters because the offspring of such a dad sell very well and by passing on the same genes over and over again, they limit the genetic diversity of the breed even more. I have found countless examples of such practices in my search for MCOs with a coi of less than 10%.
Breeders of pedigree cats are much more willing to buy an animal from another, distant country because it matches their idea of what the breed looks like, rather than looking at inbreeding.

​Why we do not practise line breeding:

What do you do if you want to improve your type but don't want the cheap inbreeding to stand out? Then you simply practise line breeding. Line breeding is nothing other than inbreeding around the corner! Cousin with cousin, aunt with nephew, etc., i.e. with cats that you already have at home and don't have to search for and buy for a lot of money. All these connections do not appear in the family tree as relatives in the direct line. This means that the line breeding is not visible on the paper pedigree that the customer receives. Especially if the cattery changes its name in between - which it can do at any time!
... "positive things are reinforced" is something you often read about line breeding - but this only concerns the type and not the health of the animals. Ideally, the animals within the litters all look the same. For the breeder and the customer, this always means the same, predictable quality. The late effects on health only become apparent to the customer after the sale. And the tricky thing about inbreeding: The reduced gene pool also affects later generations, as recessive defects can always reappear!