What exactly is the amount of culture needed to achieve legendary culture? Thanks in advance.
So, if you want easier and earlier (as for the comparative dates) culture games, the quick speed lends to that practice.
Well, this would be correct if the culture output for your three culture cities were available from turn 0 and on a constant level throughout the game. Which it isn't. If you have a look at HoF culture victories there's hardly an advantage for quick games. I'd say it's actually quite the contrary...
Quick games favor peaceful types of games where builds don't need a travel time like units.
And I don't think the main issue is to keep your empire defended, but to get those three high quality culture cities up as soon as possible...