e. make sure that a competent person performs a duplicate inspection of b. to d.
Yes, and for that person's sake, present them with the maintenance instructions for the airplane, so they can be confident that what they are agreeing is good, is actually what the maintenance manual says it should be! I've known the second set of eyes to not really know what they are looking at, and the first person really didn't either! And I have seen, and test flown, incorrectly rigged planes....
The one (a Cessna 206) had a very difficult to detect, but rather critical rigging error. I check it myself, and did not see it the first time either. When the mechanic told me he had corrected it, I insisted that he accompany me on the next test flight. He resisted, I insisted. It still wasn't right, once in the air, he then agreed with me! Eight hours later, it was correctly rigged, and flew properly!