I am a big advocate of "sole authorship". That being said, the line is generally drawn at the point where the maker can produce a piece that is distinctly their own, while at the same time not taking sole authorship to the point where the knife/knives become so expensive that nobody could afford them. Were sole authorship taken to the utmost degree, there would be few who could afford that particular piece. Suffice to say that with the base components, one individual produces the knife.
The simplest terminology I can think of is that all work that concludes in the production of a knife , is accomplished by one individual. That includes ALL the necessary steps in production.
My biggest reason for being a "sole authorship" maker is heat treating. I could never get over the situation where someone puts their blade(s) in a box, ships them off to someone, and then has no idea of exactly what those blades where subjected to between the time they left the shop, and the time they returned. My mind set is that if my name (and reputation) are going on that particular knife, then I need to have total control over it, from beginning to end! That way I can ensure that everything is as it should be, and on the other side of that coin, there's nobody to blame but me, should something go wrong.