IMO, the Vuichard technique has merits, but it is an advanced manuevre that would waste a student's time learning during a PPL course. They need to know the signs of onset of VRS and how to prevent it from occuring, and the basic recovery method.
It is similar to doing 0 airspeed, or reverse autorotations. Yes, it can be done, but really, most of the time it is instructors showing off their skills.