Usually, I think I mastered other courses within 2 weeks at most, but this course seems to be a comprehensive collection of all the fundamentals, so it took me more than 3 times longer to complete just one 2-hour lecture. It was such a great course that I could really chew, tear, taste, and enjoy. Just like math and other studies, fundamentals are so important, and this became an important course for rebuilding those fundamentals. When reviewing, I have a strong feeling that while listening to this course, if I think "Oh, I'm confused about multithreading," I can branch out like a tree, go back and review that part, and then return.!