I don't know if this is the answer, but I have an idea. When you are editing a profile, there is a link over to the right that says:
Link to free-space profiles of family heirlooms, cemeteries, houses, etc., with links like this:
Then if you click on it, you get a form to fill out about what your Free space is for. You may not have realized that you were even doing it -- it probably felt like you were still adding to the profile you were working on.
I honestly have never created one of these pages myself, so I'm not sure if they are easy to delete or not. It might be convenient, though, for adding photographs that (perhaps) show the entire family, and that you want to link to for all of the people in the photo...) or notes that you need to follow up on. I'm hoping that someone who has actually created one of these deliberately can give a better answer.