I work with one author who had the plot take an unplanned left hand turn and then had no idea how to bring it back to where she wanted it to go. We sorted, discussed, shuffled and created a story board that incorporated the turn much later in the story. Now its a matter of writing the additional chapters to get to the turn.
Her version of the story board turned into something much more than most authors would use however. The basic outline turned into a list of chapters, each having a page of its own with notes on what had to happen to get the story where it needed to be. Those got printed out and pinned over the desk, and as ideas occurred while working on one chapter they got added to the lists so as not to get lost in the maelstrom inside her head.
I am sure this would be too cumbersome a process for someone like Sasha who does well writing on the fly, but for this gal it works.