>50 hives an acre seems pretty extreme to me
It certainly does now...
But here is an excerpt from The Bee Keepers Review, volume 18, 1905
"How Many Colonies Are the Most Profitable in One Location?
"...while Mr. E.W. Alexander (review, page 60 1904) says that overstocking is a myth, and is getting a good average crop from an apiary of 700 colonies, others are of the opinion that not more than 100 or 150 colonies should be kept in one year.
"My experience is that, in many localities, during the main honey flow, where a single variety of honey-plant is present in large quantities, and all these plants are covered with unnumbered blossoms, 1,000 colonies may probably give the same average honey-crop as 100. During this flow especially if the season is a good one, such a locality can hardly be overstocked. The difficulty arises during the light honey-flows in the spring and fall. In the spring a few colonies may gather enough honey for stimulating the bees to brood-rearing--possibly a little more--but a larger number of colonies may not find even enough honey for such stimulation. The consequence is, that such colonies are not in the best condition when the main honey-flow commences, and the average honey-crop...
"...whether it is more profitable to let the bees alone, and keep 100 colonies only in one place, and the same number in several other places, or to keep a larger number in one apiary and do spring and fall feeding, spreading of the brood and several other kinds of 'play work.' I have found it more profitable to start out-apiaries, and I keep my bees now in five yards."--L. Stachelhausen, The Bee Keepers Review, volume 18, 1905