In the Book of Songs system, sentence patterns are mainly four characters, and there are also two characters, three characters, five characters, seven characters and eight characters. Why are there no

In the Book of Songs system, sentence patterns are mainly four characters, and there are also two characters, three characters, five characters, seven characters and eight characters. Why are there no six words? I don't know exactly. This should be related to the rhythm.

This is not only the sentence pattern of The Book of Songs, but also the development of China's ancient poetry: The Book of Songs has four words, Chinese poetry starts with five words, then seven words, and only a few games have six words.

Except for the four-character rhythm, all words longer than the four-character rhythm are divided into two or three paragraphs (the same is true for eight words, not two-character rhythm), and it seems that six words can't be distinguished.