The wiki claims that Port Carnelian grinding is at least 2.1 EPA with an optimal strategy, and I’ve been trying to do the math on this. This has always been a pain, as the rounding in rewards means going for more Delights or Horseheads can be less efficient. Now it’s even worse. Before, Delights and Horseheads were worth the same, so the best options were those with the highest net changes. Now, cashing in Delights also gives Tribute, so a lower number of Delights is sometimes better than a higher number of Horseheads.
I’ve been doing this grind a lot in the last few months, and with implementation of the court of wakeful eye, have switched strategy from getting as close to the 106/176/246 marker of either currency to simply taking the striped delight reward every time - 5 tribute is quite significant, and with the last four steps being fairly large conversions, it turned out to be easy to just not cash in horse-heads. You want some leftovers to jumpstart the next turn anyway, and this way it just means that amount can be a bit more, but nothing gets lost except for the rounding itself, so it makes sense to try to get closer to the lower threshold than to always aim high.
As far as actual calculations go, I was under the impression that this was simply an experimental value, item value divided by actions after some long grind sessions. There was an impressively large excel sheet linked somewhere.
The tribute part is fairly easy,of course, if we assume the numbers are large enough to ignore travel costs - 24 action carousel for 5 tribute, 20 tribute with an additional four actions to cash in pays out 62.5 E, so in sum 62.5E/100 A = .625 EPA on top of the carnelian grind itself. As far as I can tell, this rivals being in London with a neatly trimmed deck, and has lower setup requirements. But then, I have not actually run any more numbers myself, just added the tribute factor to the numbers on the wiki.
One notable thing was the ability to resupply insights via christmas cards over the holiday, that was a significant boost to EPA for the ‘A dangerous source’ option.