Broiler Or Leghorn ?

[Thomas Lamprogiorgos]

One of the top Araucana breeders here in the states has bred siblings to maximize certain traits. She has the best birds and has the ribbons to prove it.
From what I understand, line breeding (son/daughter back to parent) is the preferred method but sibling breeding can be done. You just don't want to make it a habit.
I am new to breeding, so someone please correct me if this is wrong.

Some breeds have the charisma to not be affected negatively by inbreeding.
Mother Nature blessed chickens.
The same is happening with species of wolves.