Earned value tracking can cause you to delay starting tasks that do not earn EV credit. With the first version of this book , for example, I was reluctant to work on the unplanned Appendix A. When i finally adjusted my plan to assign EV credit to it, however, I had no further problems. Promptly assign EV credit to essential new tasks. Conversely, if some partially completed task is no longer necessary, drop the remaining work on that task from the plan. Remove the earned value for the deleted work and incrase the value of everything else you have done