One thing needs to be inserted here that I don't think anyone has brought up. While doing sideslips to falling leaf, or during a transition between turns, it makes a difference whether the skier has held onto the old counter or is skiing square to the skis.
--With the old counter (the skier facing more downhill at release), the lower body will tend to unwind and drag the flattened skis around. This does not involve the skier is using active, muscularly-driven femur rotation. The skier can control the rate of this unwinding.
--Without that old counter (the skier is square), the tips may seek the fall line but the reason is different and the rate of turning is going to be slower.
--Without that old counter (the skier is square), if the skier wants the tips to seek the fall line at a faster rate than they naturally want to go, then active, muscularly-driven femur rotation will be needed. This can devolve into the dreaded quick pivot entry if it's accompanied by fear of speeding up in the fall line.