Simple Messages
Business writing allows you to break up simple messages into multiple paragraphs for increased readability. If you can express an idea in one sentence, then a one-sentence paragraph is fine.
Start a new paragraph every time you have a new idea, a new subordinate idea, a new supporting detail, another example, or a new clarification.
The goal is whitespace; simply dividing one long paragraph into multiple short paragraphs adds whitespace, which makes messages easier to read.
Complex Messages
Students of academic writing often learn to structure long, complex paragraphs with the MEAL plan. In workplace writing, you can follow the same structure, but divide a long paragraph with a heading and short paragraphs.
Main idea = heading or sub-heading
Evidence = short paragraph(s)
Analysis = short paragraph(s)
Link to main purpose in writing, if necessary = short paragraph