Continuing this conversation with @OogieM in a new thread – and inviting Obsi users to point out other community plug-ins they find useful.
Dataview brings notes alive by gathering metadata (both freeform and formal) inserted into individual notes utilizing a simple query language to add summary notes, graphs, and other features. Very powerful but easy to learn.
MetaEdit is a utility that helps with managing Dataview and YAML fields. A good companion plugin for Dataview. Not essential, but helpful.
Checklist combines checklists across notes into a single note for tracking.
I prefer separate vaults – the decision for me is about the same as the decision for “when do I need a separate DEVONthink database”. There’s no rubric for making that sort of decision – it depends on what makes sense to the user.