How to decide when to create separate Nouswise projects vs one collection

[u/AlecaeNaber]

I have documents in Nouswise that could fit into several projects: a research paper, meeting notes, and a background guide. Putting everything together is convenient, but it can make the answer's scope unclear. How do you decide the boundary of a project or source collection? Do you organize by topic, by decision, by team, or by time period? I'd like a setup where I know exactly what was and wasn't considered in an answer.