But yeah, once you get to the late exploration or modern, especially with the increased base yields, adjacencies are starting to feel a little weak. With bonuses and policy cards, if my choice is a +8 observatory or a +9 observatory, and my civ is pulling in 450 science a turn, that's not really worth it. Even if you packed in 4 specialists, that extra adjacency is only worth like 3 science total, which might even be less than the base science yield from overbuilding. Never mind the "hidden" yields like the +1 science per quarter that you get from a university, you really start getting some very diminishing returns on placement and how much the map matters.