Change is a constant. However, I see no point to the constant PCSing, PCAing, management rotations, etc. that causes a loss of corporate knowledge! It is occurs for the "sake" of a military or civilian's career, but it seems like it happens at the expense of the mission and taxpayer.
Each time a person moves, corporate knowledge is lost and so much time is spent training and bringing a new person up to speed. It is rare in DoD for someone to keep the same job in the same organization for more than 3 years. People that do stay in the same place for a long period of time feel somewhat punished because they are at a disadvantage for future promotions.
Why are all these moves necessary? If funds are spent upgrading a position after an individual spends a certain amount of years spent doing a job successfully, it would be so much better than the massive amount of funds spent moving people, training people, and all the other costs associated with yearly turnover. If the current system was efficient way to do business, managers in the corporate world would be moving every 3 years. It doesn't happen so frequently in industry so why is it cost effective for the government?