Anyone who's read my own analyses of genre and mythos would certainly find that I've used the principle many times myself. In this essay, I asserted that despite the presence of elements relevant to the adventure-mythos in both DOCTOR WHO and STARGATE, I thought that other elements dominated the tonal quality of each serial, so I did not define either series as falling within the "adventure mythos."
My method is not appreciably different from Coogan's. In various essays I've stated my takes upon the Fryean mythoi, described those ways in which I differ from Frye, and assembled the dominant traits of each mythos just as Coogan puts forth what he deems the dominant traits of the superhero genre. Then, just as Coogan does, I suss out whether or not a given work matches a given mythos. Unquestionably a lot of this sussing-out process for both of us has a subjective aspect. Another author, hip to the basic terminology of genres and mythoi, might demur from my conclusion and conclude that STARGATE is indeed a work of adventure.
My own "superhero idiom" list depends on this exclusionary process as well. When I listed my 20 best "superhero idiom" films, I did list the initial STAR WARS trilogy as one of them, and got a complaint from one poster for calling STAR WARS a "superhero film," which was not quite the point. I also got this response, which believe it or not I just noticed today:
If Star Wars is a superhero film, then so is Lord of the Rings or Harry Potter or any movie where a character has fantastic powers, which are half the movies in the fantasy/sci-fi genre. Basically, your defining the superhero genre so widely as to make it near meaningness. You also forgot BATMAN BEGINS, the best live-action superhero movie in the past decade or two.
The poster obviously had not read anything else I wrote, since I think I've been clear as to why I don't consider "any movie where a character has fantastic powers" to be within the superhero idiom. I'm not offended by that, but I find it interesting that I was accused of being too inclusionary. In point of fact, in the above cited essay and elsewhere, I've excluded all sorts of works from being within said idiom, yet have included many works within it in which characters don't have "powers" but merely something like a costume, a special weapon, etc.
Yet I'm heartened by the poster's comment, because in my reading it may means that I'm not being too hidebound in assigning arbitrary boundaries to my conceptions of the mythoi. Though I've met Peter Coogan and admire his work for comics scholarship, I do think that he's tried to hard to make it seem as if genre-constructions are objective facts, which is why he can so roundly dismiss Buffy the Vampire Slayer as a "superhero," not to mention many of the characters of the pulp-magazine era, regardless of whether or not they wore costumes or had powers.
In my view the advantage of the Fryean mythoi is that they are focused not upon narrative tropes, as are many discussions of genre, but on the emotive and expressive appeal underlying those tropes. Too often in critical history this or that emotional tenor is ignored or set aside for being too "childish" or too "fascistic," with the result that, say, only the most ironic of ironies are esteemed by some critics.
So though I do use exclusion in my own way, I believe I balance it out with a pluralist's inclusive tendencies.