Plans become obsolete so quickly because there is too much emphasis on trying to create a perfect change plan. When the stakeholders and change team spend too much time planning, they run the risk of convincing themselves that the plan is perfect. Then they hit a wall of change resistance when they put the plan into practice.
Curiously, there are two human nature phenomena at play here: the commitment bias, which is the same fallacy that forces us, by way of cognitive dissonance, to find more value in things that we had already invested considerable amount of energy into. The second phenomenon is brought on by the first, and it's that in such situations people who are good at deflecting blame end up winning.
