There are only 8 sentences in the seven-character rhythm, not 16 sentences. Representative works include Cui Hao's "Yellow Crane Tower", Du Fu's "Ascend the High", Li Shangyin's "An Ding Tower", etc.
Among the eleven poetic types of Chinese classical poetry completed by the Tang Dynasty, there are only two types, namely "Seven-Character Rhythm" and "Seven-Character Rhythm". They have very few examples and lack influence in the history of literature. Therefore, they are How to position it as an independent poetic type in Chinese classical poetry is still an open question. Among the two, the reason why "six-character quatrains" are not popular is mainly because there is no "rest sound" (rhythmic vacuum) at the end of the sentence, so there is no activation of rhythm; at this point, I think it is basically recognized objective facts.