When a plane takes off around 90% of them are off course. This is because of wind, physics and general weather issues.
The plane (project) is put back on course by signals from beacons (project reviews) and changes are made to put the plan (project) back on course. It lands at its destination successfully…(like your project)
Among other things, you have to ensure you take notice of the signals from the beacons to ensure that you land at your destination.