Because Harry was exempt from the end-of-year exams, he spent most of his time in the hidden training room alone, practicing his swordsmanship and learning any new spell he could think of that would help him in the Third Task. He really didn’t want to rely too heavily on magic- but Ludo Bagman had heavily implied to the champions that killing anything in the maze was not going to be tolerated. All of his spare time was spent in one of two places; the library where he would comb through all sorts of books to find any spell, hex or curse that might be useful, or the training room where he practiced what he’d written down. Surprisingly, Harry learned every new spell incredibly quickly, like he already knew how to do it. He wasn’t complaining though- it meant he could focus his attention on more things.