Under "Site administration > Appearance > Navigation" there is an admin setting $CFG->navshowallcourses, labeled "Show all courses". Its help text reads "Setting this ensures that all courses on the site are shown in the navigation at all times."

However, if you activate this setting, it still limits the number of courses shown in the Navigation block to the number set in the "Course limit" field, $CFG->navcourselimit.

The help text for $CFG->navshowallcourses suggests that if it's ticked, you should see all the courses all the time, effectively overriding $CFG->navcourselimit. We should implement that, or alternately, update the help text so that it more accurately describes what $CFG->navshowallcourses is supposed to be doing.

Replication instructions:
1. Create a Moodle instance with 10 courses in it
2. Go to "Site Administration > Appearance > Navigation".
3. Tick the box for "Show all courses"
4. Set "Course limit" to 5.
5. Enter a course and look at the Navigation block

Actual result: You will see only 5 courses listed in the Navigation block