I strongly believe that, prior to execution of any projects, several rounds of planning and review of milestone should be conducted. The project manager should take into consideration possible delays and set back which are out his/her control and plan according. He should have this mindset commonly used in the military: ” if you are on time, your late” Therefore, his planning should set the last milestone prior to the deadline of the project. However, if for some unforeseen reason, the project happened to be delayed, I think it will be regarded as a failure. The negative impact will be less apparent if not working in a business critical environment.