This gives the typical round-trip latency for this circuit under normal conditions, the figure an admin would quote when asked how fast a PVC is, or use as a baseline to detect gradual degradation by comparing successive polls over time. For example, a circuit whose cktRtAvgDelay creeps from 2000 to 6000 microseconds over several weeks, even without any single dramatic spike, signals a slow degradation, perhaps an increasingly congested trunk on its path, worth investigating before it becomes a customer complaint.