Even when thought the same swordsmanship, all humans develop differently. As for 自分, he developed his swordsmanship to focus on setting his sword from A to B in the shortest amount of time. Thus, 自分's swordsmanship is blindingly fast w minimal movement. Furthermore, w/ Deceptive Sword Techniques, 自分 can make his attacks seem faster than it actually is, effectively shortening 相手's reaction time