Paragraph variation is just as important as sentence variation. A long string of paragraphs with the same number of sentences or words makes for dull reading. Pick a page in the last book you enjoyed and examine it. You will see that the paragraphs varied in length. Varying the length of your paragraphs breaks up monotony in your prose. That’s the full purpose of variation in your writing.
There are caveats, however, as always. You should always use the number of sentences to complete your thought. That said, you often need to write more to make yourself clear. Sometimes you don’t. That is what leads to paragraph variation. Don’t pad out short paragraphs, leave them as long as they complete the thought.
That said, you don’t need to pad your writing with words to make all your sentences and paragraphs to be uniform. You don’t want uniformity. You want to keep your readers engaged. If they are presented with too much uniformity, their eyes will glaze over and they will stop reading. Your goal is to have your readers finish reading your piece, not get bored and wander off to another story.
Variation is part of what you need to keep your readers reading. That is, after all, your goal in writing the piece in the first place, isn’t it? To have someone read it?
To that end, you should do your best to write in the best way possible. No one will read boring prose no matter how interesting the topic. If the writing doesn’t vary in some way, the writing will read as stale and that leads to reader boredom. A bored reader will stop reading. Not something a writer strives for.
Look for paragraphs that visually look similar that are too close together. See if you can break up long paragraphs or combine short ones. That’s how you work to vary your paragraphs. That’s in the revision stage. If you can vary your paragraph lengths in the first draft, great, but if you can’t. You have revision. That’s all you need to do.
Interspersing long and short paragraphs will relieve tedium in your writing. Say what you need to say and start a new paragraph. Repeat the process. Complete your thoughts in each paragraph. Then start another paragraph for the next thought. That’s how you build a piece, word by word, sentence by sentence, paragraph by paragraph. Once you do that, you will find that your paragraphs will vary naturally.
Don’t think that you have to have evenness in the length of your paragraphs, you don’t. That evenness contributes to tedium, which is something we writers want to avoid at all costs. Relax, enjoy the process of writing. The variation will come and if it doesn’t, then revise. It’s as simple as that.