Only one VBS project at a time?

I am looking for specific documentation on how to handle projects and workspaces in VBS. I remember when I was first learning about Redwood, I was told that only one project should exist at a time, but I'm trying to understand the why behind that. Also looking for understanding on how workspaces should be used within a project.

Can there be multiple workspaces, and only one workspace published, or does the whole project, no matter if everything is ready or not, get published?

What if I create an additional project to test some things, but don't publish it? If I find something that works, I can add it to the 'main' project for publishing.