For the contest for the schools, set by the king to test them. . . .
The great challenge, the one that impresses people the most, is to devise a test that proves to be exactly what the kingdom needs by way of spellcraft. The harder it was to see, the more respect it brings.
Which does create a certain tension between the desire to play to your school's strengths to win a victory, and trying to look good yourself.
I think by the time of the story, the only question which school masters are foolish enough to convince themselves that it's obvious that what will be needed is what they teach.