Schedules are certainly one of the most powerful benefits of Revit, as they allow a level of management with a holistic perspective that allows us to focus on consistency. But there remains a gap in this purpose: those model families and types which are not in use
There's no need to imagine how to do it, or how to turn them on/off, the best way is the known one, and we already have two examples quite useful to imitate: the unplaced rooms or sheets. So it would be as easy as powerful to have the same three icons (Show/Hide/Isolate), to manage those model and loadable families which are still not used in the actual project or, even more, including linked files