“Vision-casting” is a dangerous undertaking. Once a vision is declared, it can be refined; but if it is changed too frequently and/or too radically, the leader loses his credibility and the organization loses its velocity. This does not mean that a leader cannot say, "I was wrong," and then reverse direction. It only means that one cannot make such radical course changes too often.
So how does a leader declare a vision when he is not certain of the details? How does he leave room for the “adaption” process? I think the leader needs to learn nuance. Casting a vision should be more like describing a destination. The leader, even when they are cognitive of an important change, should learn how to embed that change within the broad perimeters of the organization's primary direction.
The leader describes a destination, the organization moves in its direction. Imagine this “vision-casting” as an arrow pointing towards that destination. The arrow's main line must be broad. This gives the organization space within which to make many shifts (if the length of the arrow is too narrow, the leader is too confined). Thus, the leader describes a destination, sets a direction, but allows a breadth of course for the inevitable adaptions.