As of this writing, there are only 5 questions with the fluency tag.
- What are effective ways to gain speaking comprehension without the help of a partner in non-english speaking countries?
- Is it possible to learn many languages at the same time and become fluent in all of them?
- Can one become fluent in a language without studying it formally?
- How to improve writing fluency
- How to practice speaking a language with no speakers?
Judging solely by the titles, I think it's safe to say we don't really need the [fluency] tag. Taking each question individually, I think:
- This question is poorly worded. It seems to be about listening-comprehension, and not about fluency at all (nor, for that matter, speaking).
- This question suffers from an apparent vague definition of "fluency." The only real answer to this question, is "it depends on what you mean by fluency." I think a strong argument can be made that, if your entire question hinges on a misunderstanding of X, then X may not be a good tag--unless, of course, the question is "what is X?", in which case X is a perfect tag (but none of our questions are asking what fluency is--at least not directly). I would tag this one as multiple-languages (it already is).
The answer to this question is obviously "yes", regardless of what definition of "fluency" one uses, as the vast majority of native speakers achieve fluency without formal training. But a definition of "fluency" would likely still inform this question well. This one should probably be tagged learning-methods and possibly informal-training, or similar.
writing seems perfect for this one.
speaking would be sufficient here, in my opinion.
So in summary, it is my opinion that:
fluency should be used if, and only if, a question is actually about the definition, or measuring of fluency itself. We have no such questions at the time, so all existing questions should be re-tagged. (But we should not blacklist fluency, as it may yet come up legitimately).
Otherwise, the tag is too broad to be meaningful, and a more specific tag (or tags) should be used in its place.
(Incidentally, I suspect proficiency may fit into exactly the same category--it's probably used too broadly, and more specific tags should be used in place.)