Originally Posted by bud heishman
I find many times an upper level intermediate as defined by PSIA could be an avid active skier who is still on a steady rise in skill development for which case needs guided practice to further hone good habits OR many times a recreational occaisional skier who is plateaued and likely needs remedial help.
The biggest factor this latter skier generally needs is to discover the "GO" turn intent and learn to initiate turning with an edge release rather than a sequential stem. For many this is a wholesale change in movement patterns and takes a tear down and rebuild of basic movements and intents.
As others have noted, there may be a multitude of reasons why the skier is an upper intermediate and not already higher on the food chain. These reasons can be things as simple as not yet having enough time to learn the next thing or as complex as deeply rooted fear issues which may take a long time to work through.
Bud has noted the common sequential movements undertaken in order to initiate a turn. He has also stated that changing this will often require a complete rebuild of both basic movements and intent.
It is common, for example, for a skier to use a stem because their stance will not allow the tips to move downhill when they release the edges. But then we must ask (and answer) why they are standing on their skis that way.
The stance issue, if there is one, may be combined with a simple reluctance to let go of the old turn until a new one is started. This also contributes to a stem. Changing this requires a change in intent, but releasing, GOing, moving down the hill, generally feels less secure to those just learning it. For many, one their main interests is speed control - they want to STOP, not GO.
(Have you ever noticed that people who are not interested in speed control don't take as many lessons, even if they don't ski well?)
As Skidude72 has noted, other kinds of work, such as flexion/extension exercises, can also greatly contribute to overall improvements in stance and movement. Many skiers don't use much range of motion when they ski, again for a whole host of reasons, and getting more movement will often lead to better movement.
Still, it's necessary to figure out why. Why are they at the level they're at? Why are they doing whatever they're doing? Answering the why will tell you what to do next.