Textbooks are great for building concepts, and would probably bombard you with a plethora of information that you might think is enough to strive in the practical world. The truth however uncovers itself the day you graduate and get an on-site job. Several graduates are surprised with the level of differences with what goes in the field, and what was taught in the classroom.
When it comes to PID control systems, the effect gets amplified due to the number of inaccuracies that need to be considered in the real world. How can one go along the PID Learning Curve, and come out an expert? Namely, by doing in field testing and optimizing on PID controls.