I thought the newer thinking was that there was a rectangle with four elements, time, cost, scope and quality. Moving any one of them will affect at least one other and may affect all three others. I would make two points for PRINCE2. If you are using PRINCE2 correctly, there is no way in which ‘a junior person’ can commit the project to any extra work. All changes must go through the change procedure, and the impact analysis will show to the Change Authority what the effect would be on cost, time, scope quality, benefits and tolerances – all this before a decision is made. If the junior tries to carry out the extra work without telling anyone, this would soon be clear by the Team Manager reviewing the time and cost used.
Another corner of the rectangle is quality. I’m sure most of us know that the first thing that workers turn to when time gets short is cutting the amount of time spent on quality checking. PRINCE2 builds quality and its checking into a project from day one, and the Quality Register will soon identify any effort to slip an untested product under the wire. Go with PRINCE2. You know it makes sense!