Nobody knows what the most useful level of approximation is.
The first step to achieving a "useful level of approximation" is to understand what you're attempting to approximate.
We're not there yet. For the most part, we're just flying blind and hoping for a fantastical result.
In other words, this could be a modern case of alchemy --- the desired result may not be achievable with the processes being employed. But we don't even know enough yet to discern if this is the case or not.
We're doing a bit more than flying blind — that's why we've got tools that can at least approximate the right answers, rather than looking like a cat walking across a keyboard or mashing auto-complete suggestions.
That said, I wouldn't be surprised if if the state of the art in AI is to our minds as a hot air balloon is to flying, with FSD and Optimus being the AI equivalent of E.P. Frost's steam powered ornithopters wowing tech demos but not actually solving real problems.
The first step to achieving a "useful level of approximation" is to understand what you're attempting to approximate.
We're not there yet. For the most part, we're just flying blind and hoping for a fantastical result.
In other words, this could be a modern case of alchemy --- the desired result may not be achievable with the processes being employed. But we don't even know enough yet to discern if this is the case or not.