I just realized that top-to-bottom also solves the problem with smearing discussed in another comment. Your hand is moving down, away from the fresh characters. By the time you move over to the next line, the top is already dried. (Especially with the time it takes to fill a line with kanji, which are denser than Latin script.)
I just realized that top-to-bottom also solves the problem with smearing discussed in another comment. Your hand is moving down, away from the fresh characters. By the time you move over to the next line, the top is already dried. (Especially with the time it takes to fill a line with kanji, which are denser than Latin script.)