Rather like the use of ultra-short sentences, writers can use a ‘one-line paragraph’ to stand out as a contrast to their longer paragraphs.
Contrasts of all kinds are often worth discussing as they create impact.The impact could be for any of the following reasons:
As you can see from the list above, one-line paragraphs have very specific uses. They should really be only used when trying to achieve one of these effects.
Overusing one-line paragraphs reduces the impact they have so try to use them sparingly.