In order to manage for overall project success, control should be exercised at a very high and aggregated level and not get bogged down with unnecessary details.
It is often the case with particularly challenging or uncertain projects that the planning-monitoring-controlling effort is minimized so that the "real work" can be done.
The key to setting up a monitoring system is to identify the special characteristics of scope, cost and time that need to be controlled in order to achieve the project goals.