What exactly was measured, and what are the limits?
On 9 September 2026 we ran 20 buyer-intent and explainer queries through a synthesized web-answer surface, the WebSearch tool, which returns a written answer plus the source set it drew on. For each query we fetched every cited source, split the page into block-level paragraphs in document order, and scored each paragraph against the answer text using inverse-document-frequency-weighted token overlap. The highest-scoring paragraph across all of that query’s sources was recorded as the observation, and we logged three things about it: the midpoint of the paragraph as a percentage of the page’s total body text, whether it was the first paragraph, and whether the nearest heading above it was question-shaped.
Six of the 20 queries produced nothing usable and were logged as misses, so N is 14, not 20. In five cases no paragraph in any cited source cleared the 0.25 overlap threshold, which usually meant the answer had synthesized across several sources rather than leaning on one. In the sixth the pages were client-rendered and returned no parseable body text. Because the misses skew toward answers with no single dominant source, treat every number here as a floor on how concentrated passage retrieval is, not a rate.
Other caveats, plainly. This is one surface on one day, and it is a synthesis-plus-citation surface rather than ChatGPT, Perplexity, or Google AI Overviews measured directly. Overlap matching identifies the paragraph most likely to be the source of a claim; it does not prove the engine read that paragraph. Depth is measured against extracted body text, not rendered pixels, so a page with a long boilerplate footer would read as shallower than it looks in a browser. At N equals 14 a single reclassified observation moves a bin, which is why the shape of the distribution is the finding and the exact percentages are not.