The AI Models Index keeps track of premium model releases from 15 top labs...

https://holdenssplendiddigests.zenbloomer.com/posts/why-do-first-impressions-fade-on-lmarena-after-launch-week

The AI Models Index keeps track of premium model releases from 15 top labs since 2023, verifying launch dates and using blind-vote checks for accuracy. Updated biweekly, it shows that the average time between releases is now 4.5 days—a 56% improvement