In a startup I was working on last year, I had a surprisingly good experience with using a json-schema in my prompt. I had to tweak the json response a bit because it was always invalid, but the issue was generally a missing colon or misplaced bracket. Data-wise it stuck to the schema very well, and cleaning up the json was simple enough that we got to zero parsing errors. I believe this was with 3.5.

Sadly, that project was a final (relatively successful) attempt at getting traction before the startup was sold and is no longer live.

Edit: Ouch, are the down-votes disbelief? Annoyance? Not sure what the problem is.