A manual for writers of research papers, theses, and dissertations, Ninth edition - Kate L. Turabian 2018

Check your paragraphs
Revising your draft
Research and writing

Each paragraph should be relevant to the point of its section. And like sections, each paragraph should have a sentence or two introducing it, usually stating its point and including the key concepts that the rest of the paragraph develops. If the opening sentences of a paragraph don’t state its point, then its last one should. Order your sentences by some principle and make them relevant to the point of the paragraph (for principles of order, see 6.2.5).

Paragraphs vary in length depending on the type of writing in which they appear. For example, they tend to be shorter in brief research reports and longer in critical essays or book chapters. If you find yourself stringing together several short paragraphs, it may mean your points are not well developed. If your paragraphs run more than a page, it may mean you are losing focus. Reserve the use of two- or three-sentence paragraphs for lists, transitions, introductions and conclusions to sections, and statements that you want to emphasize. (We use short paragraphs here so that readers can more easily skim—rarely a consideration in scholarly writing.)