This sets how many consecutive RM-cell-generation intervals can pass with no traffic before the NRTS processor declares that circuit idle. Lowering this threshold makes the card reclassify quiet circuits as idle faster, freeing scheduling resources sooner, while raising it toward the max of 8 keeps circuits that have brief lulls in traffic still treated as active, so an admin tuning this is balancing resource reclamation speed against avoiding premature idle classification on bursty-but-active circuits. For example, lowering cardNrtsIdleCktThresh from 8 to 2 on a card with many low-duty-cycle circuits reclaims NRTS scheduling resources faster during their quiet periods.