The beauty of the digital world is scalability. Certainly each lecturer that spends 20 minutes doodling this, all combined, is repeating more effort (and 'wasti

The beauty of the digital world is scalability. Certainly each lecturer that spends 20 minutes doodling this, all combined, is repeating more effort (and 'wasting' more time) than Steven expended making this presentation. Someone only has to do this once, in the 20+ hours it takes, and any individual student in the world can peruse it. Or any lecturer in the world can make use of it in their class.