One-Sentence Paragraphs

One-sentence paragraphs are something I encounter often in my work as an editor. In skilled hands they are a tool for emphasis and driving a point home. But they can also indicate a need for a writer to put more effort into organizing content and providing context and transition to enable readers to follow in the author's thought process.

If one-sentence paragraphs provide emphasis, then a stream of such paragraphs gives a staccato effect emphasizing everything and thus nothing. The result is not unlike the old, Dick and Jane readers. For example:

Capitalize proper nouns. 

These include names of people and places.

Brand names are proper nouns.

Trademarks are a special case. 

Don't capitalize names of everyday objects. 

The anti-pattern I more commonly see is that of an author putting down thoughts whenever they happen to occur during the writing process. Such thoughts often show up as one-sentence paragraphs as in the following passage:

Capitalize proper nouns. These include the names of people and places. For example, "New York City" is a proper noun. 
Brand names are proper nouns too.
Don't capitalize words for everyday objects. For example, "Suspension Fork" and "Bottom Bracket" are not proper names. It's fine to speak of "suspension fork" and "bottom bracket" in lower case when talking about bicycles. 
Trademarks also may need to be capitalized.

The remarks on brand names and trademarks in this passage are disjointed and out of place. The remark about brand names can be reworked and merged into the paragraph about proper nouns. Whereas the special case of trademarks can be made in the form of a footnote. 

Here's the passage in a form that readers can better follow and digest:

Capitalize proper nouns. These include the names of people and places. For example, "New York City" is a proper noun. Brand names (1) like "Pepperidge Farm" are also proper names and should be capitalized. 
Don't capitalize words for everyday objects. For example, "Suspension Fork" and "Bottom Bracket" are not proper names. It's fine to speak of "suspension fork" and "bottom bracket" in lower case when talking about bicycles. 
(1) Trademarks are a special case. Write them always in precisely the case specified by the trademark holders. Hence we write "eBay", "iPod", and "LEGO". 

One-sentence paragraphs are legal, and even desirable. But use them sparingly. And use them for the right reasons. 

Emphasis is a good reason.

Otherwise, rethink any one-sentence paragraphs and consider whether they are better off being expanded into multi-sentence paragraphs, merged into other paragraphs, or made into footnotes. Your writing will flow better, and readers will find it cleaner and easier to comprehend.