Current ETPS teaching is to trim the a/c straight and level, clamp the stick in the centre, and then to roll the aircraft with the rudder for a spiral stab test. When that approach came in I don't know, other than it was before the mid 90s.
What JF's trick on his students does, is emphasise that the results from pure academic tests are not always truly representative of a real aeroplane in service.
G