A few months back when I shot the video clips for Card College 1 the ebook at Giobbi's house, Roberto told me a little bit about his philosophy behind Card College.
Card College should not be an encyclopedia of all moves or principles with cards. Roberto spent a long time selecting what he wanted to put into Card College and made many hard decisions leaving certain things out. His selection was partly pedagogically motivated partly his own personal choice and preferences from decades of experience and study.
One could fill another 10 volumes if one wanted to cover all moves and principles such as marked cards, stacks, ... and a zillion of moves and variations thereof.
I very much agree with his thinking. A good teacher must make a selection of what to teach. Otherwise the focus is lost. Once the student has acquired the basics and advanced skills he is ready to find and explore anything beyond that himself.
But who knows, maybe there will be a vol 5 and 6.
Chris.... Lybrary.com preserving magic one book at a time