I have for 2 years: 3-4 months in BA, then 3-4 months in the States, and repeat. I've actually REALLY loved that lifestyle -- a few months is just enough time in either place to get bored/fed up enough to be grateful for the change in scenery. It's hard on friendships, though, and you do start to feel somewhat out of the loop (I'd get back to the States and be like, "Wait, who died? Who got married? What season is it? Well, gotta go!") I'll still be going back and forth -- from now on between Madrid and Buenos Aires -- but I'm hoping for more of a 9/3 schedule instead of 6/6 (as my patience with BA has, unfortunately, steadily thinned over the last couple of years.)