How often do you need to update your site for AI to keep citing it?

There's no fixed date — what matters is that there are real changes and that they're declared: dateModified in the schema of every page that actually gets updated, and a sitemap with a real lastmod. The gap shows up clearly: a University of Toronto study measured that the three leading AIs cite content between 30% and 52% fresher than what a traditional search engine offers for the same question.

On consumer electronics, the same study measured the real age of cited content: Claude cites articles with a median age of 62 days, GPT-4o 80, and Perplexity 90 — versus 130 days for Google searching the same question.

Does the pattern hold in other industries?

For automotive, the same study measured an even bigger gap: median cited age was 148 days (Claude), 162 (GPT-4o) and 217 (Perplexity) — versus 493 days for Google. The proportion holds, even though the whole industry moves slower: a car's information changes less often than a phone's, and yet the AI advantage over Google widens instead of shrinking.

Why do AIs reward recency?

The study doesn't give a single cause, but it leaves a clear clue: in both industries, Claude and GPT-4o concentrate their citations on "earned" media — specialized press and independent review sites, not official brand pages — like TechRadar, Tom's Guide, RTINGS and CNET for electronics, or Consumer Reports and Car and Driver for automotive. That type of source republishes and updates content far more often than a static product page. The pool an AI can cite as "the latest" is already skewed toward what gets updated often.

What Nostos measures here

Unlike other criteria, here Nostos doesn't score how "new" the text sounds — that isn't verifiable — but structured update signals: the dateModified field declared in the page's schema, and the presence and validity of a sitemap.xml with real lastmod dates. A site can read as up to date and declare none of this; to an AI, without the structured declaration, that update doesn't exist.

What to do with this

• If your site doesn't have a sitemap.xml with real lastmod dates, that's first — it's cheap to implement and Nostos's own case showed a direct 14-point jump.
• Declare dateModified in the schema of every page that actually gets updated, not just its original creation date.
• Update content for real, not just the date: the study measures the real age of cited content, not a declared date with no real change behind it.

An AI doesn't cite you because you claim to be up to date — it cites you if it can verify it. The declared date and the real content have to say the same thing.