The thing is, you have to understand fully, about inbreeding. What it does, what it doesn't do and what it achieves.
There is unfortunately, a whole of of myths and stories, about inbreeding. Most are not true. Inbreeding DOES NOT CAUSE problems!!! And that's a fact. Remember those three words. What it 'can' do, is show a breeder something which might have lain hidden in the line for years. If an offspring shows up with something undesirable, then he knows not to pursue that line of inbreeding further. If an almost perfect specimen shows up, then he can be fairly sure, that that colt will be prepotent for all his attributes.
Inbreeding, can set 'type'. A type the breeder desires to have in his line. A type which is going to be probably, very prepotent.
Wayward Lad, is an offspring of a mare bred back to her sire. Very common to breed this type of breeding in many breeds, if the breeder wanted to produce something like Extra Special or Vijay.
Payton could be be expected to look a lot like Petrena and have her good points and also faults.
Vitesse is a very common type linebreeding. This is what most breeders do. It won't necessarily produce something prepotent for type though.
In outcrossing, one really never knows what to expect. The offspring can look like one of the parents or neither.
Breeding is all about knowing as much as possible, about every horse in the first three generations. Every horse. After that, not a whole lot matters, but the more one knows, the better.
Whether inbreeding, linebreeding or outcrossing, the breeder should have knowledge about the horses they are breeding and those in the pedigree.