The run-on sentence is often the subject of some confusion. Though a writer can seem to run on and on and on, each thought flowing mercilessly into the next, it’s not a run-on unless it lacks an internal separation of each thought. Thus, as authorities such as Grammar Girl might suggest, “I had lunch you did not” is a run-on despite its brevity because it’s two thoughts that run together. “I had lunch but you did not” or “I had lunch; you did not” is correct.
Which is not say that you can simply throw in some punctuation and all is well. Thanks to the semi-colon, we can string together all kinds of thoughts and be good little writers. But should we?
Take this sentence that came to me for editing:
The resort offers several convenient amenities: complimentary international calls; complimentary Wi-Fi all over its properties; smart technology in all of its meeting spaces and an easy-to-navigate mobile application that provides access to food and beverage menus from bars and restaurants at each property and resort navigation showcasing precise locations and points of interest, on-property events, spa menus and property information.
I don’t know but you, but I need to lie down for a moment and catch my breath.
Strictly speaking, the sentence is correctly punctuated. Independent ideas are properly separated by semi-colons. But it takes a bit of work to be sure that everything really is in its place. And it’s just plain too long. Couldn’t the writer have cut this into a couple of sentences?
Better (with some wordiness fixed as well):
The resort provides complimentary international calls and free Wi-Fi all over its properties. It offers smart technology in all meeting spaces and an easy-to-navigate mobile application giving access to food and beverage menus from bars and restaurants at each property. The app also has resort navigation showcasing precise locations and points of interest, on-property events, spa menus and property information.
People don’t have the time to carefully read your words and be sure they’re absorbing them correctly. Give your reader a break and keep your writing simple and direct.