Rather than go for the mega-turn, you could also go for the semi-mega turn and go Fortress/Bishop Golden deck style. A deck consisting of X + 1 Fortress and X Remake can gain 2X Duchy/Duke. Obviously once you get that once, you probably won't get it again due to the added green. But in a Duchy/Duke race, after that initial plunge getting a single Remake/Fortress is another 2 Duchies/Dukes. That is nothing to scoff at. I'd imagine in a game where both players are vying for them, you would want to set up your deck to get them faster and more consistently rather than all in one fell swoop. If you wait too long your opponent could easily win the Duchy split rendering you helpless.