Is what we read about GEO true?
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Only in part. Among the most widespread GEO advice, some are confirmed by studies and our measurements, such as the low number of citations of Reddit and YouTube by ChatGPT. Others do not hold up when measured: schema.org markup, the Q&A format, and the llms.txt file do not get a page cited. And many figures circulate without their context: the "+40%" of GEO comes from a simulated engine, and studies that seem to contradict each other often count different things. What we read about GEO is true when you know for which AI, for which type of question, and with which measurement.
For what type of question? It all depends on the advice, and the question asked to the AI. Advice might hold up for a question that names a brand and fall flat for a market question. This page confronts the most widespread assertions with what we measure through the API of three AIs.
The "+40% visibility": a laboratory result
The most frequently quoted figure about GEO comes from the paper that coined the term, accepted at the KDD conference in 2024: GEO could increase visibility by up to 40% in generative engine responses. This gain was measured in a simulated engine, where GPT-3.5 writes its response from sources that are already provided to it. It measures a page's share of the response, not its chances of being found by the preceding search.
A benchmark presented at NeurIPS in 2025, C-SEO Bench, concludes that most conversational optimization methods are largely ineffective, often harmful, and that their gains decrease when multiple players adopt them. Our own measurements show the step that the "+40%" ignores: with ChatGPT, about nine out of ten pages brought back by the search are not cited.
Schema.org, FAQ, llms.txt: three tips that do not hold up
Adding schema.org markup is one of the most frequent GEO tips. Ahrefs, by comparing in 2026 pages that added it to control pages, measured no net increase in citations, and Google writes that no specific markup is necessary. In our measurements, between 12% and 31% of pages cited by Claude and Gemini carry no markup. Writing in a Q&A format does not hold up either: between 74% and 93% of pages cited by Claude and Gemini have a title that is not a question.
The llms.txt file, presented as a way to guide AIs, has no demonstrated effect. Google writes that it is useless to create text files for AI. On sites brought back by AI searches across about ten sectors in French, we measured that cited sites do not publish a llms.txt significantly more often than others, and the gap changes direction from one AI to another.
Reddit, YouTube, Wikipedia: true and false depending on what you count
We read that Reddit, YouTube, and Wikipedia are the preferred sources of AIs. This is true for what ChatGPT brings back, not for what it cites. In our measurements, pages from these three platforms brought back by its search were cited between 0% and 1.5% of the time depending on the corpus, compared to 10% to 15% for other pages. Ahrefs, using another method, found the same order of magnitude in April 2026: 1.93% of Reddit pages and 0.51% of YouTube videos retrieved by ChatGPT end up being cited. Two independent methods agree.
Contrary figures often count something else. The "47.9%" attributed to Wikipedia in ChatGPT is only its share among the ten most cited domains; of all citations, the original study gives 7.8%. A share of citations, a share of responses, and a share of the most cited domains do not measure the same thing, and most contradictions between studies come from there.
Google ranking: a real link, but one that is weakening
We read that AI responses use the top Google results. For AI Overviews, Ahrefs measured about 76% of citations coming from the top 10, then 37.9% in March 2026, using a different method that requires cautious comparison. For ChatGPT, the link is much weaker: only 8% of the pages it cites appeared in Google's top 10 for the same query, according to Ahrefs in August 2025.
What our measurements show for ChatGPT is the weight of rank within its own search results: a page in the top three ranks is cited 6.9 to 8.5 times more often than a page beyond the ninth. The advice "be well-ranked" is therefore correct for Google, and needs to be reformulated for ChatGPT: you must be well-positioned on the searches that the AI writes itself.
What AIs did with this question
We asked ChatGPT, Claude, and Gemini the question "Is what we read about GEO true?" without any other context. ChatGPT and Claude asked which GEO we were referring to, and neither of them thought of Generative Engine Optimization: ChatGPT looked into the credibility of GEO magazine, all the way to its publisher and a Pakistani news channel of the same name; Claude searched for international organizations and reports bearing this acronym, relating to the environment and Earth observation. Gemini answered first about the magazine, then mentioned Generative Engine Optimization as a possible second meaning.
The lesson holds true for any business. A short, ambiguous question is read in its most widely known sense, and the cited sources follow this interpretation. That is why this page relies on our measurements of other questions rather than on this collection: the cited sources mostly related to another subject.
How to read GEO advice
Before following advice, ask four questions. Which AI does it apply to, since ChatGPT, Claude, and Gemini do not choose their sources in the same way? What type of question, since a question that names a brand is not handled in the same way as a market question? What was measured: a share of citations, a share of answers, a correlation, or a control-group effect? And was the measurement repeated, since answers change from one time to another?
Advice that does not answer any of these questions is an opinion. Advice that does answer them can be useful, provided you do not apply it beyond what it measured.
What we do not know
Our measurements cover the API of GPT-5, Claude Sonnet 4.6, and Gemini 3.5 Flash with web search, not their applications nor Google's AI Overviews. We have not tested any optimization recipe on a page: we observe what distinguishes cited pages from discarded pages.
Sources
- Aggarwal et al. — "GEO: Generative Engine Optimization", KDD 2024, .
- Puerto et al. — "C-SEO Bench: Does Conversational SEO Work?", NeurIPS 2025, .
- Ahrefs, Louise Linehan — adding structured data and AI citations, .
- Ahrefs, Louise Linehan — "Why ChatGPT cites pages", .
- Profound, Nick Lafferty — "AI platform citation patterns", .
- Ahrefs, Louise Linehan — AI Overviews citations and top 10, .
- Ahrefs, Louise Linehan — overlap between AI search and top 10, .
- Google Search Central — "Optimizing your website for generative AI features on Google Search", .
- FaireDuBruit measurements, from September 4 to 16, 2026 — see "How we measured".