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

https://oliviasinsightfulthoughts.novacrestiq.com/posts/is-openai-actually-steady-on-release-cadence-or-does-it-swing

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