I recall reading in the Chicago Manual of Style that the ideal line length for printed sentences was between 65 and 72 characters. Alas, I cannot now find that citation, but there is much interest on sentence length on the net. Here’s just one article (external link). The point is that readability is a subject of study and has been for decades, for centuries even, ever since Gutenberg. In this Internet Age we think we can design as we will, but that ignores common rules that the print world has always observed. In a time when a website can be viewed on a phone, a tablet, and on a desktop machine, we must be constantly reminded of how our words and sentences appear on a screen and how our readers are trying to understand them. I’m not a web designer so I do not know how to standardize sentence length on my websites. But I try to stay aware of the similarities and the very real differences between computer and paper.
Have you ever proofread an important report? Especially a long one? It is amazing how many errors one can find when the paper is printed. There is something about how the eye jumps back and forth, this way and that, catching things at the top and bottom of the printed page, seemingly instantly, that is not done on a screen. We miss things in the small window of a computer. Even when looking at a full page screen you still find mistakes on the print-out that you will not catch on a monitor. Which brings me to another point.
If we cannot fully catch all mistakes on a monitor, can we fully understand what we see on a screen? Screens are really meant for looking quickly, often just a paragraph or two at a time. We browse or graze on a computer, instead of taking it in fully like with a book. Does this mean we have to print out every long form article on the web? No, but it does mean we should think about whether we are reading or reading well. And that we should probably put our web writing into small chunks, with illustrations to help explain the text, and enough repetition to get our points across, even if we didn’t get them across in the viewer’s first reading.