You should probably look at the cost/score graph by effort level instead:

https://artificialanalysis.ai/models/claude-opus-5-5#intelli...

It is most of the pareto frontier.

Disagree. Our internal company tests showed a cost per task drop from 0.35usd to 0.16usd . Opus 5low vs opus 5.5 low

I don't think so, I typically use Opus 5 on High, and 5.5 scores lower on token use:

https://artificialanalysis.ai/models/claude-opus-5-5?models=...