@JESinstr, you post that video so much that you should put the link in your signature!
One could claim that any drill can cause unwanted ingraining, which, while possibly true, is most likely only for those who do not know what they are doing a drill for in the first place, what the correct form indicators are and whether or not it is has been successfully mastered. Some people have “favorite” drills they do all the time which may not be a good idea because it is time to move on once a drill or a difficulty level modification has been adequately mastered and there is no reason to keep doing it which is probably a reason why a drill may become “over” ingrained. If you find yourself at the same level of drill execution everytime you go skiing, this may be an indicator of a lack of any significant improvement. Three caveats I would include to this sentiment are for aging skiers who need “maintenance” and those warming up for the season or the morning, but not for straight development.
Ski drills challenge and improve three assets: Strength, balance and coordination. These three assets also function as correct form indicators as to whether they are challenged or mastered. The drill demo Josh is executing masterfully requires strength, balance and coordination that are significantly connected to the fundamentals. If anyone of those assets are challenged and not met, the result becomes very obvious that the skier has yet to master the drill. I have noticed over the years many aspiring skiers shy away from doing anything on skis that makes them “uncomfortable” such as direct challenges to their strength, balance and coordination. Feeling weak, unbalanced and uncoordinated are the sensations we should be seeking when looking to improve through doing drills. Anyone who has a spine for it has the opportunity to improve much more than the many that do not. Challenging our strength, balance and coordination outside of drills with our regular skiing can be found to be a dicy and risky affair in a much less controlled environment.
Josh does this drill two ways, something I would organize as two separate difficulty modifications. Keeping the inside foot off the ground is the easier version, at least for me. Entirely disengaging and re-engaging the inside foot within every turn is more tasking to strength and coordination though, it may be said that engaging only one ski in the turn requires more balance. For a skier to determine the order of difficulty for their particular skill set, they would first need to try both versions, first working to master the easier version and going on to work on the one that is more difficult.