In most cases, it is not good to write horizontally, because 8k paper is relatively small, and the content that can be written is very limited. You also need to consider the choice of typesetting and fonts. If you use cursive script, it will appear that Chinese characters are crooked and not neat enough, and because of the structural problems of Chinese characters, they are not good-looking.
Using vertical writing makes it easier to make the font layout straight and keep the consistency of upper and lower lines. No matter what font looks neat, and the font size is different, the writing effect is different, so vertical writing is better than horizontal writing.