At the Maple Ridge workshop last weekend, Master Chen went over again the mini lessons he covered in his Edmonton Full Time videos.
Master Chen demonstrated that tossing and double heavy is the same mistake. I used to think that double heavy is only applied when doing a linear move, pushing and pulling.
But in there is also double heavy, if the is not rooted like a screw driver, then it is double heavy and not effective in Push Hand. The reason it should be spiral down is to keep opponent locked in his position, then there will be a tearing force against him.