Good question. I find that GPT-5.5 thinking is very good at not thinking for simple questions, so much so that I've never had the need to use the instant model even for quick Q&A.

I'm assuming the instant model, then, is an entirely different smaller model mainly serving the free tier of ChatGPT.

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simianwords 5 hours ago | parent [-]

It is an entirely free model, but it is also the model that most users (even paid) interact with until the router pushes the thinking.

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pants2 5 hours ago | parent | next [-]

Good point. I feel like this does a disservice to ChatGPT -- IIRC even the free tier of Claude points you to Sonnet 4.6 by default, which is magnitudes better than 5.3-instant which has been the default in ChatGPT.

Hence most users will immediately think Claude is smarter, even if their best models are on par.

	▲	simianwords 5 hours ago \| parent [-]
		then again I think the free sonnet 4.6 only allows ~5 requests a day but GPT allows more than 50

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while_true_ 4 hours ago | parent | prev [-]

Correct. I have the $20/month plan and I just checked, the default is 5.3-instant. I can manually switch it to Thinking is 5.5. I also have it set to auto-switch.