The AI Models Index tracks premium model releases from 15 labs since 2023,...

https://lanesniceblog.scriblorax.com/posts/why-does-gpt-5.2-cost-more-than-gpt-5.1

The AI Models Index tracks premium model releases from 15 labs since 2023, verifying dates and using blind-vote checks for accuracy. Updated every two weeks, it shows that in 2026, new models arrive every 4.5 days—a 56% speedup from before