The first thing you should know about reading in college is that it bears little or no resemblance to the sort of reading you do for pleasure, or for your own edification.
Professors assign more than you can possibly read in any normal fashion.
We know it, at least most of us do. You have to make strategic decisions about what to read and how to read it. You're reading for particular reasons: to get background on important issues, to illuminate some of the central issues in a single session of one course, to raise questions for discussion. That calls for a certain kind of smash-and-grab approach to reading. You cannot afford to dilly- dally and stop to smell the lilies. You might not think that's the ideal way to learn, and I would sort of agree. But on the professorial side of things, we feel a real obligation to cover a particular field of knowledge in the course of a semester, and we cannot do it all through lectures. Nor would I personally want to talk at my students day in and day out.
Skimming For Arguments: Introductions, Conclusions, Signposts
The first rule, in some ways the only rule, is skim, skim, skim. But skimming is not just reading in a hurry, or reading sloppily, or reading the last line and the first line. It's actually a disciplined activity in its own right. A good skimmer has a systematic technique for finding the most information in the least amount of time.