GOTM 31 Spoiler I - End of Ancient Age, Map of starting continent.

[SirPleb]

I will post some details in the Middle-Ages spoiler, but my first estimate is that the doubled culture points will only contribute 10 to 20% to the final cpt.
Which is not negligible, of course; but the risk is that in order to achieve this, one abandons further expansion and finds himself with only the most expensive buildings left in the last 20 turns or so.
This, in turn, means that the cpt increase in these last turns drops significantly and there is no way to improve the final date.

The key parameter here is in my opinion the culture 'acceleration' throughout the game -that is, how many culture buildings can be built during each turn: in order to balance the very low cpt of the first 100-200 turns, it is vital to be able to keep it increasing at an increasing rate during the last ones.

Interesting! I think that's true, continued acceleration is necessary. And it can best be acheived by having enough towns. As AlanH said, settlers are a more important use of shields.

I've come up with another way to look at that tradeoff: A settler + temple + library costs 170 shields and produces 5 culture/turn. A university is the next best improvement (after library and temple) - it costs 200 shields and produces 4 culture/turn. Settling more cities and rushing the cheaper improvements clearly wins over settling less and rushing the more expensive ones.