Do not trust planning tools
We are all using planning tools such as primavera and Microsoft project. However, you should always remember that they are just tools, and the result comes from them need to be verified before considering it correct.
Modern planning tools could be very useful, at the same time very harmful as well. For a positive outcome, we need to check at various stages that it makes sense. One of our professors during college days defined an Engineer as ‘Problem Solver with high Engineering Sense’. Though modern technologies help make life easier, it shall not be allowed to reduce our engineering sense. Out of my experience, I came across a fatal error in the time schedule because of the fact that the fellow Planner did not check the planning tool precisely.