A slightly different take on parts of the LeMaster pic...shots #3 & #8 the skier is not really on the tails. At the transition the skier flexes deeply to release the old turn. This flattens the skis for the release, but due to our stiff boots the skier's body must be behind the feet. Because the skier is so light on the skis at this point it isn't really skiing on the tails. Shot #7 is different, we can see the snow spraying from the tails.
"In order to start a turn effectively, we need to move our Center of Mass forward to bend or balance over the shovel of the skis. We must start the turn by engaging the tip of the ski, so we look for “getting to the front of the ski” at the initiation." Again a slightly different take. It might be more accurate to talk about the vertical alignment of the skier's center of mass over the skis' sweet spots which is somewhere forward of the toe bindings. We want the skier's mass over the forward part of the skis to initial the turn, or the forward part of the skis under the skier's mass. The difference is in how one accomplishes this. Here is where the pull back of the feet does the job, pull way back and pull back early as an initial part of the new turn initiation. Somewhat the same for the end of the turn. We want the back part of the skis (but not too far back) under the skier's mass to jet the skis forward at the end of the turn. A slight push of the feet forward does this followed by the release then a strong early pull back to begin initiation of the next turn.
50+ years ago is the first time I heard about jet turns. The ski is loaded in its curve during the turn, then with the skis pushed forward at the end of the turn the curve straightens and unloads and jets forward. We've all probably felt this inadvertently and didn't know why those skis shot our from under us when we had a sit-back moment. Back in olden days Jet Stix were sold, long stiff upward extensions of the cuff behind the calf, so one could load the tails of the skis even more to jet forward at the end of the turn.