A pattern that I see over and over again in my freelance editing work is the run-on sentence. This construct is a trap that many authors fall into. After all, it is extremely tempting to try and say everything you want to say in a single sentence because there are so many benefits and wonderful thoughts you want to share with the reader in an intelligent and comprehensible manner.
That last sentence has 41 words. I've seen sentences that are much longer. This is something that you want to avoid in your writing, or worst case, use sparingly. Consider it only if there is simply no coherent way to separate out the thoughts in that one long sentence.
The Reader's Perspective
Readers actually prefer shorter sentences as a general rule. As a writer, it can be difficult to do but every once in a while, step back and attempt to read your work as a pure member of the audience. This is best done after taking a break, perhaps a walk, and then returning with a relatively fresh perspective.
The cadence of shorter sentences makes for pleasant reading. You develop a flow, and the reader can expect to learn new constructs, ideas, or thoughts as they go. Each new concept builds on top of the previous points made earlier in the text.
The challenge with longer sentences is they potentially can do the following:
Disrupt the flow of your narration or prose
Cause confusion regarding which phrases refer to which objects
Obfuscate the main point that you were actually trying to make
Ideal Sentence Length
The majority of your sentences should be 20 words or less. You can allocate roughly a third of your sentences to run longer than that. I would avoid having sentences that go longer than 40 words as a general rule. To see why this is, take a look again at the introductory section of this article and the 41-word sentence placed there. Is that easy to grasp and comprehend? Or enjoyable to read? By the time we reach the end of the sentence, it is no longer obvious what the adjectives intelligent and comprehensible refer to.
In the section above "The Reader's Perspective", the breakdown of sentence length is shown below. At only 14 words per sentence on average, does the cadence feel comfortable to you? is it easy to read? Try rewriting it using longer sentences and compare the two approaches to see what you prefer as a reader.
Why do writers tend to run-on?
There are a number of possible reasons. A few reasons include:
You have so many things you are excited to say, you try to pack it in all at once.
You consciously or otherwise fear that shorter sentences seem too simplistic.
You have not yet organized the flow of thoughts you want to communicate.
I catch myself doing using run-ons at times like all other authors, so I try to be cognizant of factors that lead to it. I have mentally overcome the simplicity reason, although I still struggle with the other two.
Don't underestimate have a clear organization of your thoughts as a contributing factor. Additional phrases added to a sentence often wander into points tangential to what you are actually trying to communicate at that time. In a person-to-person conversation, these hanging phrases might be articulated in the form, "Oh, by the way, this also does some other wonderful things." This can dilute or even confuse the initial set of wonderful things you are telling your audience.
Putting these techniques into practice
Don't be afraid to use shorter sentences. Developer a cadence with a comfortable flow for the reader. Plot out your ideas and have them build upon each other as you proceed through your text. You don't have to explain everything worth telling all at once. Your readers will appreciate you for it.