A sentence is a held breath. The longer it runs, the more the reader has to hold — and most readers, kindly, simply let go.
I used to mistake length for depth. A clause stacked on a clause, a parenthetical tucked inside a subordinate aside, the whole thing held together by commas and good intentions. It read as thinking. It was mostly throat-clearing.
What length hides
Long sentences are a wonderful place to hide a weak idea. The reader is busy keeping track of the grammar and never quite gets to ask whether the point was worth making. Cut the sentence in half and the idea has to stand on its own.
If you can cut a word, cut it.
George Orwell, paraphrased
Try this: take your longest paragraph and put a full stop wherever you naturally pause to breathe. You will lose some music. You will gain every reader who was about to give up.
Rhythm, not rules
This is not a vow of monotony. A short sentence lands hardest when it follows a long one. The craft is in the variation — the long swell, then the sharp turn. But the default should be short. Make the reader work only when the idea is worth the work.
Write long to find the thought. Then cut until it breathes.