ECG/EKG Tech vs Monitor Tech

I recently got certified as an ECG/EKG technician through a coursework that primarily dealt with single lead interpretations, all Lead II in fact. The certification agency was the NCCT. The program says I should be qualified to apply to be a ecg/ekg tech and a monitor tech. When applying for jobs, monitor tech positions do not mention 12-lead interpretations only familiarity with basic arrhythmia. However, when inquiring further it seems that I DO need to be adept in interpreting all 12 leads.

The NCCT exam and coursework I took all focused only on lead II, was I scammed? What exam should I be taking and what coursework would train me to be adept in reading all 12 leads?