Unfortunately, in practice that works only most of the time. At least in our experience (and the article says something similar) sometimes ChatGPT would return something completely different when JSON-formatted response would be expected.

I've been using the same prompts for months and have never seen this happen on 3.5-turbo let alone 4.

https://gist.github.com/BLamy/244eec016beb9ad8ed48cf61fd2054...

In my experience if you set the temperature to zero it works 99.9% of the time, and then you can just add retry logic for the remaining 0.1%