Yep, all good.
Most of the time, I will have one fixture per model, but not always. It's a quick and cheap way to test url patterns in a one or two line test for example.
A fixture can return a list of items, None items, or even a dict of items if you want. It's pretty flexible and it just depends on the test or the modules.
I use bakery in tests too, if it's cleaner.
So we might have good_shopping_cart or incomplete_shopping_cart for instance.