3 x 4 minute miles is a great workout. that's ultra elite territory.
rod dixon saw pre run a couple of 358 mile repeats, google it for more info.
dixon himself, reported by arch jelley ran a couple of solo sub 4 minute miles on grass at the auckland domain.
those guys dixon walker and pre, viren if paced right, peaked right would go close to 13 flat for a 5k.
i guy like rono would go 12"5x for sure, with any real method to his madness.
such is life back then, they never laid down the times.
even a coe never cam close to running his best 1500.