>You could also have CPU-bound code, such as performing an expensive calculation, which is also a good scenario for writing async code.

That's a scenario for a different reason though (to allow sharing the cpu between chunks of the calculation, e.g. to not freeze UI in JS). In that case you might want to async on CPU-bound code.

But regarding maximizing utilization, you want async to take more advantage of a core's CPU when you got tasks waiting for IO, and threads to leverage more CPU cores when doing CPU bound tasks.