For categories with more than one page worth of courses, there needs to be a "Show All Courses" button to change the view from showing 20 to all.
This is incredibly handy for course creators & administrators who have to do bulk actions on all courses. Which I have to do once a month on a client site...
Currently, I have to set the perpage=20 to a different value (I normally pick perpage=20000000). But this is just a cheeky URL hack.