In a movable object system (10) that makes use of both a maintained count (31) that corresponds to movement of a given object and passpoint events (32) as generated by a corresponding passpoint signal generator (15), count zones (34, 37, 36A, 36B) can be defined for at least one of the passpoint events. Such count zones can be used to aid in determining when significant recalibration of the passpoint event/count value relationships should be undertaken. In a preferred embodiment, such count zones include no more than a single passpoint event.