The problem is that the Kubernetes CPU scheduler is... not great.

There are many instances where it will throttle CPU of a pod way before it even reaches the requested amount, let alone the limits. This is only true if you set limits. If you don't, it will always have the requested amount available, plus whatever can be spared that's not in use by other processes. It will throttle at most down to the requested amount, and in most cases not at all.