We're in the 19th century still. In fact just a couple of years after the last text I regurgitated for you.
"The Distribution Of Hops.
When boiling in a single length, all the hops would be added directly the wort boils, or very shortly after, in the case of running ales, and of such beers as are relatively lightly hopped, and in which the delicacy of hop flavour is of secondary importance. In the case of pale ales, however, as has been already stated, it is well to retain about one-tenth to one-sixth of the hops for addition about a quarter of an hour before turning out. These latter hops—which should be the most delicate of those used—will contribute their full amount of hop oil, the period of boiling being insufficient to expel any appreciable fraction of it The spent hops from a single boiling, are either sparged in hop-backs, or pressed, to wash or extract from them the wort which they hold, and the bittering principles which they are yet capable of yielding. The pressing of hops, however, is not advisable, except in the case of the very finest. Inferior hops yield under this system a coarse and harsh bitter flavour, which is distinctly disagreeable.
In the double copper system, it is advisable, in higher class ales, to split up the hops between the first and second coppers, generally in the proportions of two-thirds to the first, and one third to the other. When a large proportion of hops is not used, a certain portion of the spent hops from the first copper can be returned to the second, and boiled together with the fresh hops reserved for that purpose. It is also advisable, and for the grounds previously stated, to reserve about one-tenth to one-sixth of the fresh hops destined for the first copper, for addition shortly before turning out As before, the residual wort and bittering substances retained by the hops can be extracted by hop-sparging or hop-pressing.
In the case of lightly hopped running ales, it is usual to put the whole of the fresh hops into the first copper, using for the second or other coppers the spent hops from the first. It is better, however, even in cases of this kind, to reserve a certain portion of fresh hops for the second copper, say one-fourth or one-fifth; for in spent hops from the first copper, the resinous matter will have become hardened and rendered antiseptically inactive, and the tannin will have been nearly all extracted. When this is done, or when the whole of the hops are added to the first copper, it is customary in running ales to return the whole of the first copper hops to the second. In these beers, delicacy of flavour is no great consideration, and any slight bitter harshness will be covered by the greater body of these beers. It is therefore well to obtain as much extract from the hops as they are capable of yielding."
"A text-book of the science of brewing" by Edward Ralph Moritz and George Harris Morris, 1891, pages 265-266.
Let's try and summarise that.
If there's just one wort, add all the hops when the wort starts to boil, except for Pale Ales, where a sixth to a third should be kept until 15 minutes before the end of the boil.
If there are two worts, for running ales, all the hops often go in the first copper and get re-used in the second. Though it's better to save at least a few fresh hops for the second copper. For classier beers, two-thirds of the hops go in the first copper, the other third in the second, with again some added 15 minutes before the end of the boil.
So, Moritz and Morris only recommend two hops additions for posh Pale Ales. See a pattern emerging here?