It’s an arbitrary number that felt high enough. If I said 10, people would argue that a frontier model can talk longer than that. But I have absolutely watched ChatGPT fall apart that quickly. I’m sure everyone reading this has.
We can nitpick the duration all you want, but we both know it does not take very long for this to occur. It happens particularly fast if you stray from the original topic and/or aren’t using a frontier model.