State your opinion inbreding or outcross

I believe either the AGA KHAN or Marcel Boussac were big on inbreeding speed on speed and bred a Derby or Arc winner that way ,whether they were inbred I am not sure.
All I know is that if you want to win a major in the RSA you had better buy from the following stallions.Fort Wood,Jetmaster,Western Winter,Al Mufti,National Assembly.Two or close to the end and if you can pick a new sire to replace any of the above you are on your way to making money.