It is a common practice that also happens to work well in many situations. With a friendly or neutral audience, this is the method that works best. For the hostile audience, however, a writer might want to adopt a different strategy. In summary, then, each paragraph needs a topic sentence, and the placement of that topic sentence will be a judgment based on audience. Good writers create paragraphs that have unity .
Coherence means that the ideas flow logically from one thought to the next.
This concept goes back to the idea of paragraph length discussed earlier. Paragraph must satisfy the reader's desire to know. If the writer is short on details, the readers will not be convinced or satisfied. Again, make the paragraph long enough to satisfy the demands of the topic and the demands of the reader. Building a paragraph involves a lot more than just indenting once in a while.