as you perform this shift onto left heel, feel the club is being thrown down the fairway ...and finish high ...ball should never go left with this technique (which was Ben Hogan's earlier swing fault)
In actually the CF is squaring right from the top ...but the last few inches are squared by the shift onto left heel ...this adds sensory completion-ness to the squaring act and added impetus to the clubface rotation i.e. more power from sweet spot turning faster than the shaft