I think I should also add that, although I'm a QAM for a sizeable aircraft maintenance company, I don't agree with joining all these "quality clubs" for the sake of getting a new badge on the wall - and I often oppose attempts to do so!
I believe that all these "Tools" do have a use. And they may highlight an area of concern, but in the main, they do not replace the use of "common sense" which waste's less manhours and costs far less in consultant fees.
My company does ISO9001 and EASA - with the emphasis on EASA - we try to keep it fairly simple, and it works.