Nah for the Moment i'm at 170% Bonus. But every day ist dropping that fast due to building Upgrades that i will drop to 140% in 3-4 days.
Next city Expansion is around the Corner but only worth 550 new culture wich will be eaten in 2 days of buiding because most buildings will reach Tier 2 this Weekend and this will be an Ultra massive increase to required culture.
I tried to figure out how it works and i have a guess but nothing really concrete. But my guess for the Moment is that you Need 300% of the culture that is actually needed to build something to reach the 200% Bonus.
How i get the roughly 300% ?
At the Moment all my buildings require 1415 culture in total to actually can be built.
These 1415 + the available culture is the total culture you "produce".
For me thats 1415 needed plus 2192 available = 3607 total culture "produced"
To reach the 200% mark i Need 2800 available culture. Which meens i would require a total of 4215 culture in my City to reach the 200% Bonus.
4215 / 1415 = 297.87985% of building culture.
But that you can break down to 300% because the required culture to reach 200% Bonus only changes every 33.3333~ needed culture because it always goes up by a hundred and not consistently.
To reach the 170% mark you Need about 235% of building culture.
But that would only work if all buildings which are not affected by culture Bonus didn't Need culture. As it is at the Moment it will be nearly impossible to reach the 200% with a decent production without using Diamond culture and constant polishes of nealy all culture buildings the whole online time.
And at the end for that culture Bonus doesn't effect your manufactories it is only worth to go to 140% Bonus without neighbourly help. 170% is possible but the space you require for the jump eats mostly the whole 30% benefit. For the 200% Bonus you would actually produce more by building additional residences and Workshops with 140% as to try to reach 200%.
And for culture requirements going up massively as you upgrade buildings ist less worth over the time.
For example you Need about 700 culture to run even ONE lvl 15 human Workshop thats 2 Workshops per biggest non Diamond human culture building. Which Needs approx 40% of the space which Needs the Workshops including the 3 needed residences.
I hope i could bring a Little light into the dark to you all
And sorry for my english - i know ist not the best and Auto correct mostly turns small into big letters -.-