the use case is where one researches a broad stream of information, and wants that - after sorting w/ help of DT-fab AI - to be (also) available in very different local / specific contexts (databases) w/o the noise a global / huge database naturally brings (as good as DT-AI) is. meaning: I can close the global db (or disregard it in search - e.g. via ‘search in this db only’), and still have available the records which I collected and pre-sorted in there (global db, ‘inbox’… however you want to call it).
– but I think I kind of said that already above.
otherwise, please elaborate what kind of ‘use case’ description is in your mind…
[addition]
when I revisited the comment anew, I saw the added (‘Kayak-framing’) request from @Bluefrog; i.e. request to spell out my ‘use-case’ even further,
… so, here is that scenario as well, though I honestly do not think this kind of background is either standard here, or is really (read: should be) needed to accept the legitimacy / relevancy of a request for help w/ a particular ‘technical’ set-up, otherwise missing in DT.
– but hopefully it at least serves some to get further ideas (as also stated by @bluefrog)
use case scenario (simplified from my actual use)
• you read and collect many multi-topical blogs because you have many interests. these interests additionally subdivide into domains (personal, professional, special interest topics etc). – so what you read could come from Thoughts&Co, Curio, Aeon, or ‘The Long Now’, National Geographic, or Physics.org… any mixed topic source like that
• these provide interesting content that could fall into any of your interest categories (vulcanos, oceans, climate crisis, aesthetics, kayaks, parallels of water-borne and air-borne ships, traditional cultures, extinction - depletion - loss, crisis of modernity, … even: interesting topical places to visit, or: strange sports, as quirky hobby 
)
• for the rather numerous substopics you prefer likewise numerous special DBs – because: you prefer to have clean search / related contents / concordance / tag-sets … and all that, once you really jump into those special topics (= spotlight-set-up of the DB in question)
• given your daily / weekly scan (= ingest / reading) of general text & info-sources you know there will be some articles that will belong into any of those or into several of those categories. at the same time there are some articles, or books/events you want to register you deem interesting, but they do not yet fall into any of your predefined topics. they might border on some of the topics, but are not strictly relevant when it comes down to it, in terms of spotlight mode (e.g. history of boating, island cultures, sports events etc.). the general DB thus is a kind of straylight DB.
• still it has some defined function: while collecting content from sources like those mentioned, you are reading / highlighting the important parts in this DB – as you want to have them marked up in a single go, even if the end up in different databases later. And as you a) either don’t want to deal with really sorting stuff right away into one of the many subtopics (databases); or b) are unsure they even really belong in any of those (yet); or c) as know they belong into many at once… you prefer keeping the first working phase (ingest / read / pre-sort) in this general DB. this way you can also benefit from the fact that the internal DT AI and the tag-autocomplete is your friend – and helps you to immediately and painlessly pre-sort the articles into different folders, w/o the work and friction of opening extra DBs now (and the work of having to remember which ones are around, re-conentrating all the time). also you value that some groups that do not yet fall into any subtopic (= do not go into a special DB for now) can grow here, regardless. and once a new category really ‘takes off’ (= the group grows; catches your special interest) you might get the idea, ‘ok, this maybe should become an extra topic… and get an extra DB eventually’.
• the way you wanna take care of that is that once you open your special topic / focus DBs you just go back to your general DB and decide which folders should from now on be ‘forwarded’ to that (it might be one of the sorting folders, or a curated set of those). and you feel relieved you can feed that DB later just by sorting into the right folder in the general DB, i.e. w/o opening and closing (and searching) specialized DBs all the time. (because there is automatic ‘mirroring’ of the selected folders from general DB into the specialized ones)
• also, in this scenario there are still these times you want to go into your special DBs (let’s say Kayak), but you want your search and autosuggest, concordance and all that to be clean… (see above)
• then, in this scenario, there are times where you want to / need to go back to the general DB for other reasons; like: you want to check whether new folders not yet acknowledged should be added to one special DB; you want to relate back your topical research to a broader horizon of discourse and information (to get new ideas; to question your assumptions, categorizations, reframe your context space etc.). thus, it is of additional vualue (besides the practical workflow) to know your special sorting groups are still to be found in that larger context
… is this what you had in mind with your request, @BLUEFROG?
Anyways, hope it helps people, possibly get new ideas, or contrast theirs.
