I certainly believe that a Blake swing, correctly executed, does make full use of both the lead and trail hands and arms.
Mindy talked at length about how the "Square-to-Square" golf swing involved putting the trail hand in a very weak position in order to prevent it overpowering the lead hand. This he believed was a dreadful waste of what might be the golfer's stronger hand (indeed, stronger side).
So, if you are not making full use of your trail side, read the book again and change your swing !!
In other posts I see mention of keeping a Blake swing slow, particularly early in the backswing. Hear, hear !! This is vital if the hands and arms are to stay relaxed (otherwise they will tighten up purely to keep control of a fast moving club during the backswing and in the transition to the downswing). The other aspect of a fast swing is that the larger parts of your body, namely your torso, hips and legs, will not be able to keep up. This will then lead to an "arms and shoulders" swing (when we know that we want the larger muscles to be driving the swing).