How often do you create a separate vault for new projects?

For about two years, I practiced storing all my notes in one place: daily notes, lecture, meetings. Even content for my hobby sites. It was convenient for me when I had a couple of thousand notes stored in one vault, strictly organized into folders.

Now I have 8 separate #obsidian vaults, of which at least two are always open. The vaults have different themes, which serve as an indicator of what I should be focusing on at the moment.