Rhythm is how long your sentences run, and how much they vary.

Claude's average sentence is as long as a good writer's. The averages hide the part that matters: whether the lengths move. On that, both versions run a little flat, and W10's rules did not fix it.

Length swing is the standard deviation of sentence length, in words. Writers in our reference set swing by about 11 words: a long sentence, then a short one, then a medium one that turns the corner. Claude swings by about 9.5. Each sentence is a reasonable size, and so is the next one.

Same brief, same paragraph. The first leans on a fragment ("Then a line marking where it went soft") to break the pace. The second keeps every sentence whole and lets them grow, 10, 8, 12 and 20 words, so the paragraph builds toward its longest example.

A drumbeat is a stretch of six sentences that are all short and all about the same length. One short sentence lands a point. Three in a row start a rhythm the reader can hear, and the content stops mattering. Writers almost never do it: about 1% of their six-sentence stretches. W10 flags each one, with the sentences.

Same brief, same point. The first ends on three sentences of 6, 5 and 4 words: the cadence of a keynote. The second still pairs its claims, but each one carries a detail ("with a small link beside it") that a slide would drop.

Long sentences are where a writer holds several things in view at once: a list of worries, a cause and its exception, a scene. Writers in the reference set put about 24% of their sentences past 25 words. Claude does too. The difference is what the length carries. A long sentence that lists concrete things reads fast. One that stacks clauses of reasoning reads like a contract.

Both run past 30 words. The first spends its length on reasoning, "and", then "because", then a comparison. The second spends it on three things a real prospect asks, in the order they come up.