Not necessarily. I include quizzes that I want hidden from students in visible modules and haven't had any problems. Maybe if you describe your thought process or what you're concerned about we can help!
I guess I am not understanding how to make sure that the quizzes are hidden until I assign them.
You can go ahead and add your quizzes to your modules and then just not publish them until you are ready for students to see them in the module. If you create and unpublished module, add content, then publish the module, be sure to check that publishing the module didn't inadvertently also publish content within the module that you aren't ready to have be visible. If that happens, just unpublish the content you still want hidden.
Here's a video I created for my faculty where I talk about draft state (published/unpublished) in Modules. See if this helps. If not, then please let me know and I'll be happy to clarify!
Ok... one more question. Next year - will I be able to get to courses that I create this year?
@shollis , in theory, yes, you should have access to the courses that you create this year. Yet, each Institution does things a a little differently so you'd want to check with the Canvas Admins at your Institution to verify that you would have access next year. If you're not sure how to contact your Canvas admins you can click the Help link in Canvas and "Report a Problem." I know you're not actually reporting a problem, but this is one way to get your question (or problem) to your Institution's Canvas Admins.
Hope this helps!