GPT-5.6 Sol was July 9 > GPT-6 Sol was September 22 (75 days)
Fable 5 was June 9 > Fable 5.1 was September 1 (85 days)
Opus 5 was July 24 > Opus 5.5 was September 22 (61 days)
Yeah, we're not due for a model refresh until the end of month if current release roadmaps of 2-3 months hold.
Leaks, for what they're worth, indicate that the next GPT model is soon (tomorrow rumored), and that Fable 5.5 is already ready-to-go. That said Fable is likely being held to drown out said GPT release, since Anthropic is already ahead w/ Opus 5.5.