And you do not have flat priced quota for Fable 5, right? Because nobody has, as far as I know. So you'll probably not route any task to the "current best available SOTA".
Also: quota. Implies you do not have unlimited access even for flat prices. Which in turn implies that as soon as you hit the quota on the most expensive flat price plan, even you will suddenly discover the magic of economically sensible behavior.
Fable 5 is included in the Claude Max subscription. I've gotten close to the limits this week and last but haven't hit it yet.
But Fable is only available for 50% of your Max quota as far as I understand