They had a roadmap and a vision until about a year before launch, when Joe Staten, and much of their original team, left. That coupled with pressure from Activision to get the game out for 2014 meant they had to scrap most of their original plans and just think things up on the fly, something that, in any sort of hardware or software development, is best avoided. With all this in mind, it's honestly amazing the game turned out as well as it did. They improved the storytelling overtime; they totally hit their raid stride with WOTM; PvP, while a complete departure from what it was in Y1, seems to have a real vision in mind now (for better or for worse). This is what Bungie always does: they get most of the way through, stumble, then start almost from scratch. They did it with Marathon, Halo CE, Halo 2 and now Destiny. It's like Valve Time, but more costly.