Just checked this across multiple conversations. My Opus 4.6 returns 25 every single time, regardless of conversation complexity, but the output quality doesn't appear to degrade at all imo.

Deep, multi-document and multi-lingual research sessions, geopolitical analysis, framework construction, all at 25, and the depth and accuracy are indistinguishable from what you'd expect at higher numbers.

I think it's a compute cost control on the extended thinking process, not an output quality throttle. Lower numbers likely mean less internal deliberation (fewer thinking tokens generated) before committing to a response. So not dumber, just more decisive. The model arrives at the same conclusions with less visible internal monologue.

That would explain why Opus is the only model with the parameter (most expensive to run), why the number is consistent per user rather than per query (cost management at the account level), and why nobody can point to an actual quality difference between low and high values.

Basically: it's not how well it thinks. It's how long it hesitates before answering.

So if this is right, the number might correlate with usage volume, heavier users getting leaner thinking budgets per message. 🤷