Filling 5 branches will take you AT LEAST until 1700AD on standard settings, assuming you get every cultural bonus possible and pick the right branches.
I just discovered myself that social policies cost increases rapidly with the number of cities you have.
Plus there are cost-lowering policy and wonder, seems like these should be aimed as well. Wonder is industry-era tho, so yeah, you cannot win earlier than that.
Scientific victories hardly even seem possible by 2000AD because there is no great way to just tech hard.
There is - research agreements. 1 free tech per agreement is great way to speed up your research. I try to keep 3-4 agreements going at same time. Plus there is policy which gives 2 free techs, plus there are some wonders giving same, and there are great scientists giving free tech each. If you slot some specialists in libraries/universities, you get plenty of those.
Yep. I've done all of these things. Making 2 workers and 0 other units the ENTIRE game, and consistently remaining allied with 3 cultured city states, and making nothing but great people, culture increasing structures, and wonders on one city, you can get 5 branches finished in about... 250 turns.
It seems to me that against any human opponent who isn't going for a cultural of scientific victory, you would get absolutely crushed, or you would run out of time. To play *reasonably* (having some military and more than one city) and get a cultural victory, you need 300-350+ turns it seems. Sadly, one you get to hermitage and the +33% culture structures, you SKYROCKET in culture, yet you only need 1-2 more policies to win
By the time you finish the utopia project you have a 6th full branch
They should increase the culture bonuses of certain mid-game buildings and decrease the 20% per city.