Only people enrolled in an known traveler program (TSA Pre, GE, Nexus, and Sentri) will be eligible for TSA Precheck. They no longer let frequent flyers not enrolled be given the Precheck flag on boarding pass nor will anyone be redirected to the Precheck line based on behavior.

Keep in mind those in GE, Nexus, and Sentri that Precheck is not guaranteed, although you most likely will get it most of the time, it is not a guarantee and there could be a chance you may not get it on the occasional flight.