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

https://technivorz.com/how-long-does-google-take-between-announcing-and-shipping-a-model/

The AI Models Index tracks premium model releases from 15 labs since 2023, verifying launch dates and using blind votes to ensure accuracy. Updated every two weeks, it shows a steady pace—like the 4.5 days between GPT-5.1 and GPT-5