When given the choice, DS also tends to solve a lot of problems, even many difficult AMC ones in his head. I have suggested to him that he at least jot down some basics to save time if he intends to go back and check. That logic has persuaded him to at least try to jot down some stuff more often that he otherwise would. Regarding illegible writing, DS is notorious in that regard, but has improved a bit;it has helped when I pushed him to not "conserve" paper - instead of using tiny patches of white space on the test page or scrap paper, I encouraged him to grab a new sheet of scrap paper.
