> Is there any evidence that central planning on a much larger scale is drastically more efficient?

If it were, why do we have more than one company?

> I take your point that companies themselves are usually centrally planned internally

Well, sort of. It is true that companies exist solely for the reason of exploiting efficiencies in central planning. If central planning was always inefficient, companies wouldn't exist! But, as I alluded to earlier, no company has found central planning to be efficient in all cases. Not even the largest company in the world centrally plans everything. Not even close.

As with most things in life, a bit of balance will serve you well.