What is the correct usage of individual works tags vs. author tags vs. franchise tags?

Question

As part of the cleanup effort to eliminate some of the more "meta" tags, there are a lot of questions that are about a specific work of fiction, and should be tagged as such, but for which no tag yet exists. It's already been pointed out that this can be an issue for lower-rep users, who can't create tags, but for the moment I'm more interested in what the higher-rep users should do.

When we get a question about some work of fiction we've never seen before, at what point should we create a tag specific to that work? In particular, what is the cut-off for creating a new tag, vs. using existing tag(s) for the author(s) of the work? At what point do we need to create new franchise-level tags and start using them?

There was a previous discussion about the usage of author tags:

What is the policy for author, series/universe/work tags?

but the two conflicting answers were voted +4/-1 and +2/-1 ... not really an overwhelming consensus. If we're going to re-tag such questions appropriately, we need to agree on exactly when each type of tag should get created, and used.

• When do we tag a question with the author's tag, e.g. brandon-sanderson?
• When do we tag a question with the name of the work, e.g. well-of-ascension?
• When to we tag a question with the name of the franchise it's part of, e.g. cosmere?
• Does the answer to any of the previous three questions change if it means creating a new tag?

Answer 1

We should be pretty liberal with creating tags for specific works of science fiction, and here's why I think so (if you don't care, skip down a bit :) )

In my opinion, a "work of fiction" is the core element of "expertise" that exists for the people supplying answers on this site. In other words, the bulk of the answers (not all, but most) start from the premise of "I have read/seen/heard/etc the given work of fiction you're asking about and know all of the details." Very often we can expand this to include "all of the works of fiction in a given series/franchise/etc", or even "all of the works of fiction by a given author", but in general, our core knowledge boils down to those things we know because we have consumed some specific piece of fictional media.

The other tags we have -- story-id, author, franchise, history-of, etc. -- serve to identify those questions where that assumption doesn't hold true, and so they should be used for those cases. But we should always strive, whenever possible, to at least identify the fictional work that is at the core of a question.

As an aside, I ran a "hypothetical" brand new book by a brand new author through our tentative tag scoring guide, and even with 0 questions it scores a +12, which is well into the range of "good tag". That assumes we've selected a good name for the tag, which can sometimes be problematic, but not insurmountable.

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So, my proposal is that we use the following guidelines when tagging or retagging questions:

• If the question is about a work of fiction, it always gets a tag; if we have to create one, we do that (give it a tag wiki, etc.) If there's confusion over what to call it, bring it to meta.
• If the work in question is part of a larger franchise, also give it that tag always. This makes it easier for people to follow/ignore/etc. one tag and cover the entire franchise. (For example, I believe all questions about MCU movies should be tagged as such, even if the question is localized to one movie, so I only have to follow one tag.)
• If the question is asking about a) aspects of the author's life, or b) aspects of the author's work that are not specific to a single work or franchise, then we tag the question with the name of the author.

Answer 2

TL;DR:

Always create tags for work and author; franchise if applicable.

Rationale

Like I've said before, tags are a question's Bat Signal. They signal which experts a question needs, to have the best chance at getting answered.

The most important experts to attract are those of the work itself. The question is about the work itself, so if there is someone out there who has studied the work in depth, they are the best expert possible.
If the tag doesn't exist, it should be created.

But of course, if the work itself is too small to warrant any experts, the next best thing is the bigger whole it's a part of. That can either be an author's body of work, or a series or franchise it is a part of.
Again, if those tags do not exist, they should be created.

And since we want to attract as much experts as possible and we don't have a tag hierarchy, the question should wear the complete set of tags.

Example

So, if there's a question about Dark Force Rising, the second book of Timothy Zahn's Heir to the Empire trilogy, which is part of the Thrawn series and ultimately part of the Star Wars franchise, it should be tagged:
dark-force-rising heir-to-the-empire thrawn-series star-wars timothy-zahn
Of these, heir-to-the-empire and thrawn-series are debatable and could be omitted, depending on the existence of other questions about the same series.