Every decade or two things change, partly because the old masters pass and the new ones take over, and seek to leave their own marks on the art (see Shuhari for more on this). Politics within the community causes splits and rifts, and many styles are influenced by how much focus they have on competition, self defense and practical applications, and/or commercial success. Some teachers are dedicated to preserving "the old ways," and teach as they were taught, but they are rare.