When you derive a project from a project in a space it is also in the space. So a copy does not end up in your personal workspace. If you delete a space though all of the projects are returned to the owners personal workspace. This is true of other peoples derived projects - and also of your templates.
For the workshop use case that sounds like the "Copy Space" feature would be helpful (what's new has directions on where to find the button). It would give you a new space with with just your workshop projects.
Sean