The closest thing to "fanning" I've heard of that is used widely is "slip hammering", where the pistol is aimed, the strong hand holds the trigger back and the weak hand brings the hammer back to full cock and lets go, being faster than pulling the trigger every time. I don't THINK it damages anything, being a CAS newbie with SASS but I've seen it done. I find it awkward and clumsy for me. Of course, this is why I win no buckles.
Edit to add, I agree - a friend who would abuse my property would find he no longer has access to my property.