Hanging tons of sound and lighting equipment above spectators and performers is a serious matter, especially in light of the trend of increasing load weight and movement.
Scientifically, each time there are more than two hoists on a truss, or more than three hoists in a structure? there will occur the state of a "Statically Indeterminate Structure", which results in unpredictable load distribution. In most cases this will cause load imbalance, where some of the hoists may reach overload while others carry only a smart part of the load
Thus, overload situations might happen to the most experienced riggers, even if each hanging point's load is calculated and the calculation falls within the limitations of the nominal hoist and truss capacity. The actual load distribution on the truss is still unpredictable and cannot be calculated, or even estimated.
The solution to the need of ensuring safe installations and shows is real-time load monitoring and overload detection.