Why do some Tang poems have six words?

In addition to our common five-character poems and seven-character poems, there are also miscellaneous poems. The so-called miscellaneous poems refer to the miscellaneous between long and short sentences, mainly three, five and seven sentences, and occasionally four or six sentences. There are not only seven-character quatrains and five-character quatrains, but also six-character quatrains in Five-character Short Stories and Seven-character Short Songs. For example, the pastoral music of the Tang Dynasty poet Wang Wei:

Hearts also contain fresh rain overnight, green willows and a touch of spring smoke.

The children at home have not been driven away, and the oriole singing the song of idleness is still sleeping.

Li Bai's spring scenery:

The door faces the crane creek, and the cloud meets the home of Yanxian.

Who knows people's affair? I'm used to seeing mountains, rivers, birds and flowers.

Six-character quatrains belong to modern poetry, but musically, compared with seven-character quatrains and five-character quatrains, six-character quatrains are somewhat contradictory, monotonous and lack of musical beauty, so they are not suitable for reciting. This may be the reason why the number of six poems handed down now is small.