Citation Half-Life

Citation Half-Life treats every answer-engine citation as a perishable asset with a measurable decay window, not a permanent ranking. A brand mentioned in a Perplexity answer today can vanish from that same query in weeks as models refresh their retrieval, competitors publish fresher pages, and source pages get rewritten. For agencies, this reframes AEO from a one-time audit into a recurring monitoring retainer: the deliverable is not a report, it is a cadence. HubSpot's 2026 State of AEO data shows marketers adapting content for answer engines while most audits still use traditional SEO metrics, which measure position rather than citation persistence. A practical test: run a client's ten highest-intent queries through Perplexity, ChatGPT, and Google AI Overviews monthly, log which sources get cited, and flag any citation that drops out. That delta becomes the scope justification for the next retainer cycle.