Name the thing
I wrote a heading I liked, then covered the paragraph. The heading said nothing you could act on. It sounded finished. It was a riddle.
Core already bans the setup sentence that only announces the next sentence. A riddle label is the same waste in reverse: it withholds instead of announcing. Test: cover the body. If the label does not say which thing this is, name the thing. The aphorism can stay in the prose if it earns a place there.
The same test works on a finished-sounding sentence you cannot repeat to a friend. "This is meant to live on a desktop you already leave on" sounds like a product. "Run it on a computer you leave turned on" is the product.
Em dashes sit in the same budget. One earned dash is not a finding. A dash in every heading, or clause-then-punchline as furniture, is. Do not treat the mark as an AI tell to erase. A comma, period, or colon usually does the job.
I now write the heading after the paragraph, or I write a boring noun first and only then see if a sharper line is still a name.