Some of you do enjoy your own opinions. While ML 16 was on the twin NDB approaches I operated in there using the 16 twin NDB app. Using LNAV & VNAV while monitoring raw data the RNP was fine but the aircraft was paralleling final. We were in VMC on this occasion & a good 2nm from ROC we were diverging from the 5* tolerance & well right of the extended centreline(trackline indicated on the centreline). Of course CWS was used to correct the track. On other occasions in IMC I had to manually correct the path in the same way. In short, sometimes with all the technology you must use raw data to correct and/or ensure tracking is accurate. If you don't you may as well trust the FMC to fly your vertical path as well without monitoring the DME etc. Checkies who test these competencies in my opinion are doing all aviation a service by reducing a CFIT incident. This air crash investigation concludes that the crew may not have properly monitored & flew by the ground based aids. Even though the B737NG reduces this risk right down, lateral tracking can sometimes be inaccurate with the FMC generated tracks, sometimes by up to 0.5 of a mile, which I have experienced.