Forgive the intrusion as a new voice. I was following this thread from its start because it's something I thought about a lot when I taught skiing, and something I still think about a lot. I've had several friends take up and/or want to improve their skiing in the meantime since I stopped teaching, and I'd witness their struggles as relative newbie adult skiers. Here's how I saw the list before LiquidFeet broke it into categories. I had broken it into 3 categories.
14. there's a misconception about who a lesson can help; many think lessons are for beginners only
SAME THING SAID DIFFERENTLY -- UPPER LEVEL -- these are subtleties to be pursued/established after the basics are nailed down
21. lack of separation, 27. lack of upper body-lower body separation (skiing square instead), 43. not knowing how to use the inside leg/foot/ski, 44. no conception of release, 45. no ankle tipping, 25. TIMING- extending when they should flex, flexing when they should extend, 32. unable to, unwilling to, or unaware of the need to produce round turns, 42. lack of long leg short leg, 28. lack of angulation (leaning in instead), 7. (in bumps) stiff-legging and waist-beinding to avoid getting backseated (intermediates)
SAME THING SAID DIFFERENTLY -- BEGINNER & INTERMEDIATE -- these are different ways of saying the fundamental problems of beginners relate mainly to a few basic points:
A) the natural human tendency to lean back into the hill and avoid free space/falling sensation when standing still in alpine terrain
B) the instinctive tendency to replicate this leaning-back reflex when skis are strapped on, and amplify it because skis are slippery
C) the instinctive, tool-using human urge to use those metal edges as brakes because they're so effective at biting into snow when put perpendicular (or relatively so) to the fall line
D) the evolution of (A) - (C), as put into practice by the self-teaching eager new skier (as well as by the intermediate with some days of skiing on the books who is "figuring things out" for himself), is to develop a defensive attitude both toward moving down the hill as a feeling/experience, and as a perspective on what the skis are for.
Getting skiers to understand (A) through (D) is primary, then helping them understand how skis actually are designed to work should be next. At the intermediate level the skier is moving toward less of the bulldozer technique, but it's not an informed and deliberate progression they're using. From my experience most do not realize they're being a bulldozer and are taking a lesson in order to stop doing that. Most just want to "look better" and/or "feel less tired (or if honest, less intimidated) when skiing _____."
To many, the linked hockey stops with a measure of grace is competent athletic skiing and the finest thing one can aspire toward. These folks aren't likely to care about maximizing what they can get out of a ski. Stable smeary turns with little edging and no angulation are what these folks crave: the very turn that makes instructors like golf carts. So picking their tactics or moves apart from the perspective of a racer, or of an expert all-mountain skier, it's not likely to be fruitful other than as a teaching tool for an audience -- like watching surgery at a teaching hospital, I guess.
I think that a human's natural tendency to lean back toward the solid earth behind him is baffling or otherwise forgotten to experienced skiers, and it's inexplicable to that 0.001% of humans who by nature and instinct dive out into open space as if they were birds. But to most skiers it's the foundational problem.
Due to this instinctive human tendency, skiers get their hips and hands aft as the body reaches for known solid earth. This puts the feet ahead, which makes the skier "late" in all ski-control tactical senses. Everything that is happening at the skis is happening before the skier wants it to happen. The skis are skiing the skier, who has been relegated to passenger status.
The more experience accumulated while serving as mere passenger on the skis, the more likely the skier cannot comprehend that it's possible to actually control the skis in any subtler or easier way. Aft and late is the norm. So what's a skier to do, but improvise while using the foundational Aft and Late Scenario?
As a result the skier tosses gross power into the situation, with an aggressive tail-kick combined with, or perhaps preceded by, an upper body windup which pulls the hips around, which pulls the feet around... eventually. But notice: this further delays the event, further reducing tactical choice and further increasing skier panic. (It all could have started at the feet! But this concept is still ethereal to our skier. Starting at the feet requires shifting from passenger to pilot. And that can't happen until our skier no longer lets feet get ahead of hips, and has stopped reaching back for the hill behind.)
For a skier moving down the hill linking these panic-induced hockey stops, skiing is probably closer in experience to running across a battlefield that is getting periodic shelling. Survival moment by survival moment, rushes of endorphin, feelings of relief. If you're an adrenaline fan, this is fun. For some skiers, this is all the fun they think they'll ever have.
If a skier wants more control and is willing to put in the work (and this should be emphasized, it requires a kind of athletic work to change these habits, and many people are not accustomed to athletic work), the goal should be to work on the new paradigm of Never Defensive, Never Late. But it has to happen on gentle slopes so the skier can pursue gliding and acceleration without feeling that impulsive braking urge. The skier has to want to feel the ski gaining glide & speed. As long as Defending Against is the perspective, the heel thrusting hockey stop urge is going to kick in, and it may induce a stem or wedge or step or hitch or hip-throw or baseball-pitcher-windup of the torso.
I would go so far as to say that Defending Against is the primary foundational problem of all beginner and intermediate skiers, and is responsible for these listed points.
3. not knowing how a ski works, so unable to get the ski to turn the skier, 4. defensive moves instead of offensive moves, 29. excess tension throughout the body; managing the turn with their muscular system rather than through their skeletal system, 30. not engaging the core while being sufficiently un-tense throughout the rest of the body, 6. inability to completely abandon the wedge and replace it with a parallel stance, 35. arms swinging; inside arm/hand dropping back, 10. leaning up hill with too much weight on the inside ski, 23. failure to flex ankles, 2. stance and balance is off (using a simpler framework), 20. Improper movement of the Center of Mass, 22. balance point too far to the rear, 34. feet consistently in front of body, and feet consistently downhill of body, 24. lack of foot engagement, 18. little or no ankle flexion/extension, 12. most skiers place a lot of weight on the inside leg, 39. skier is back and inside, necessitating a big body move to get down the hill, 1. sloppy turn entries (beginner through intermediates), 9. not having patience thus skiing defensively; patience is a big part of offensive movement, 19. Improper (and often too early) pressuring of the outside ski, 40. using big movements to control the skis rather than subtle movements to allow things to happen, 13. a "rush to action;" not using patience to allow the progressive development of the turn, 37. “pushing the tails” as a way to initiate parallel turns, 16. hurrying the turn entrance, 5. skiing from the back of the ski with no tip pressure, 31. skiers don't create flow from one turn to the next (a traverse between turns; a dead spot between turns; rushing of the top of the turn), 8. inability to effectively release the old outside ski (at all levels), 17. upper body rotation, 41. upper body rotation, 26. up unweighting, 33. pivot and brace turn mechanism, 11. people push on their skis too much, jamming them in at the bottom of the turn, perpetually riding the brakes, 38. skis are seen as a braking tool, and not a turning instrument, 15. jamming on the brakes instead of beginning turning movements at the top of the turn for speed control