To teach the approach using the PAPI, as the standard, to ab initio students is not a good idea. If you are to use the PAPI as a guidance it is important to understand them. Some are just two lights (APAPI) and not four: in which case you are either right or wrong, there is no graduation. The most important thing to understand is that the PAPI is not required to be set at a fixed distance from the threshold, such as 300m nor provide 50 ft above the threshold. The height given at the threshold (MEHT) must be published however and meet defined limits if they are approved for instrument approaches. For these reasons it is most important that the student learns to use the visual clues always available, such as the runway shape, and also be aware of the obstacle heights of the approach and departure profiles.
What is important is that the student learns to assess the touch down from the POH/AFM and factored, for the given conditions on the day, and therefore that the correct airspeed is maintained on the approach. PAPI/APAPI are of course invaluable at night although not essential. The runway lights can give you all that you need regarding the runway shape as guidance.
I think the term "ollocks" is correct.