ChatGPT's crawl frequency depends on which of OpenAI's three user agents is fetching — GPTBot crawls on OpenAI's own schedule for training, OAI-SearchBot crawls to keep the ChatGPT Search index fresh (accelerated by IndexNow via Bing), and ChatGPT-User only fetches when a specific user prompt triggers a live retrieval.
OpenAI has not published a public schedule for GPTBot; frequency varies by site, popularity, and change signals. Server logs typically show GPTBot returning every few days on active sites and much less often on stable pages.
OAI-SearchBot is the more actionable one for AEO. Because ChatGPT Search is Bing-backed, an IndexNow ping on publish surfaces the URL to Bing within minutes and, transitively, to ChatGPT Search's freshness layer. Publishers routinely see new URLs available for citation the same day.
ChatGPT-User is on-demand — no schedule at all. It fires when a user asks ChatGPT to open or read a specific URL.
Practical measurement: filter your access logs for each of the three user-agent strings. That gives real crawl frequency for your site rather than a general estimate.