By now, Tu Dinggui has formed a fairly complete guess about the Exam Institute's intention behind setting up this test.
The existence of any exam must inherently be to assess certain abilities and knowledge of the examinee. In this practical test, it's undoubtedly to examine some "practical skills" of the Magical Girls.
The maze before them now clearly simulates the scene of a Remnant Beast's nest.
Since a Remnant Beast's nest will somewhat distort the surrounding space, a Magical Girl must have sufficiently strong perception ability to find direction within it. Hence, the form of this test is a maze, to optimally simulate the state within a nest.
In nests of Remnant Beasts at the Half-Molt level and above, rules come into effect, requiring a Magical Girl to have a clear mind and calm head to analyze and break these rules. Hence, so many puzzles are scattered in the maze, purely to select talents who can continually ponder further questions during exploration.
