Most of the problem is that for voice chat, you usually get no reasoning at all and no tool use at all to research or ground assumptions.

For example for voice ChatGPT still uses a quantized gpt40 non-reasoning model that hallucinates pretty frequently. It also doesn’t do much automatic search for updated information and fact checking.

I usually don’t find I need high, usually DeepSeek v4 with medium reasoning is sufficient.

However if it’s important chat like brainstorming on complex topics I sometimes bump it up.

OpenAI has a new voice api that supports adjustable reasoning, but ChatGpt is not using it currently.

With a sufficiently sophisticated harness you can actually do quite a lot by just talking to your AI. I have regularly dictated to build things on my phone while walking to lunch for example.