GPT-5 was supposed to make choosing models and reasoning efforts simpler. I think they made it more complex.

> GPT‑5’s reasoning_effort parameter can now take a minimal value to get answers back faster, without extensive reasoning first.

> While GPT‑5 in ChatGPT is a system of reasoning, non-reasoning, and router models, GPT‑5 in the API platform is the reasoning model that powers maximum performance in ChatGPT. Notably, GPT‑5 with minimal reasoning is a different model than the non-reasoning model in ChatGPT, and is better tuned for developers. The non-reasoning model used in ChatGPT is available as gpt-5-chat-latest.