Why can calligraphy write a single word, but not a whole paragraph?

This is the composition of calligraphy. For example, the density in the overall layout is line spacing, word spacing, the size ratio of different words, and the relationship between words. Composition is one of the three elements of calligraphy. Good composition can improve the artistic effect of the whole calligraphy work. Even if some words are not perfect, they are coordinated and fluent on the whole.