I won't be able to add anything "new" to the thread, but one of the major themes I saw emerging throughout the posts were the problems associated with random lessons. A number of people mentioned cost being a prohibitive factor, but it appears to me that the real crux of the issue is that you pay good money for a lesson and if it turns out to be a complete dud the odds of repeating go down significantly.
In my own case my wife and I moved to UT and took up skiing after having never done snow sports. To give you some perspective we are both fairly athletic and in our late 20s. One of the big advantages that I recognize in our case was the ability to ask around town about good local instructors. As a result, we landed what turned out to be one of the top people for both skiing and snowboard instruction at our hill. In what I think was around 5 hours of instruction over about the course of three weeks he set the foundation for our skiing that would eventually culminate in my wife skiing at level 5 and myself skiing solidily in level 6 (and the beginnings of level 7). I cannot imagine trying to improve without having someone like him setting us up for success.
Now, it's probably important to include that we skied with some very good skiers afterwards and skied alot, but I returned to him over our opening weekend this past week to work on my goals for this year. In another hour chunk we worked on improving my skiing through chopped up pow and began the early stages of how to handle the trees (which is where my friends spend 100% of their time). Even though we didn't require a lot of instruction the fact that we were able to establish a relationship with an instructor that we can continually return to has been a big part of our quick progression.