As with all these questions, it's complicated and I don't think there's a single rule that fits all circumstances. In many cases consistency is a false god to which utility is sacrificed.
If you're asking about Civil Registration in England and Wales (or about Probate records post circa 1858) all you need is an England-and-Wales tag as the records and the process of locating them are the same across that geography (as long as you tag for the record type -- maybe we need a civil-records tag).
If you're asking about Parish registers (or Probate records prior to 1858) then you probably need a country tag and a county tag as the process of locating the records varies with county (which is a proxy for diocese). (I hope nobody is suggesting diocese tags!)
Some geographies need multiple tags -- Israel and Palestine and British-Mandate-Palestine are not the same place, even though they occupy overlapping land albeit at different times. Looking for a marriage record in Palestine is a different process to looking for a marriage record in British-Mandate-Palestine.
I think the fundamental guidance when tagging for geography should be:
- Does the geography matter to the answer? If not, don't tag for
- Do one or more geographic tags help questioners find similar/related questions that might let them answer their own
question or at least expand their knowledge in area of interest; and steer them away from rabbit-holes; (See my example of
Palestine versus British-Mandate-Palestine).
- Do they help experts find questions to which they can contribute expert answers (I know a fair bit about the availability of records
for Pembrokeshire, but nothing about Monmouthshire, for example).
Or do they just summarise the question (which is a tagging no-no)?
Is the geographic tag at the lowest relevant level for an answer to be targeted and at the highest level for an answer to be as
applicable to as many related questions as appropriate.
- If the OP has tagged at the wrong granularity, an expert ought to fix it.
- If the tag is ambiguous (Birmingham, for example) it should be disambiguated unless the ambiguity doesn't matter (in which case it
probably doesn't need a geographical tag anyway).
(As an aside, using two tags for geography can be constraining on other tags when there's a maximum of 5, so we might want to consider combined tags such as England-Worcestershire, or USA-New York State. Consider tag sequence: England, Warwickshire, birth-records, civil-records, 19th-century, locating-records -- which one should be dropped?)