On our installation each term we have around 1500 courses that we cannot open to students until the day the term starts but needs to be open for instructors well before to prepare content.
I know that when you show and hide categories it can also show and hide courses within it but that doesn't always seem to work as some courses could be opened and closed by instructors and no longer be affected by the showing and hiding of courses.
I've built out the ability to accomplish showing or hiding all courses within a specific category. See here http://tracker.moodle.org/browse/MDL-33781
I've added two more icons on the Add/Edit courses page that will allow showing or hiding all courses within that category.
Does anyone think this is useful. If so please vote and maybe this could be added to core.