Maybe you are a student, so let me give you some advice. The working out of the problems is not a meaningless task - understanding the problem solving methods and the underlying structure of the mathematics is important. You are right, engineers in the real world are not expected to do the calculus, they have charts and graphs and rules of thumb, many shortcuts to the "right answer". But the reason we train engineers the math is so they don't make a big mistake and kill somebody. Being able to work the shortcuts alone is not good enough, it's scary, because it means you don't really know what you're doing.