I don't like the lower left quadrant of that diagram, because it's not clear that it's not centered on the target. It would have been more clear if the cluster

I don't like the lower left quadrant of that diagram, because it's not clear that it's not centered on the target. It would have been more clear if the cluster was smaller so it could be moved to not be centered on the target. Accurate but imprecise means we can throw more and more shells down range and eventually hit the target. Inaccurate and imprecise means we may never hit the target. Inaccurate but precise also means we may never hit the target, but if we could introduce a second, different measurement that was accurate, we could compensate.