Many games you can plan when to trigger your GA.
I will oftentimes play Ottomans because I like its UU, Siphai, which comes along in place of cavalry -- later in the game.
This past game, I fought a couple of early wars to get some cities. Then when Siphai came along I built them, but did not use them (since a Siphai victory would trigger my GA), until I researched Industrialization -- for factories.
By coordinating my Siphai war with the discovery of factories, I triggered the GA so that most all my cities were putting in factories during the GA. As I had built up Siphai in the intervening techs between cavalry and factories, and since Siphai are such incredibly vicious attackers, I waged war during about half my GA, all the while getting factories in place in most of my cities at "half price."
At least with Ottomans, this strategy worked out really nicely for me. And set me up to go grab Theory of Evolution to slingshot to Electronics and Hoovers "just like that." While taking out the Mongols with my Siphais.