CLRS is the size of a reference manual. Algorithms courses tend to cover material from it, but never the entire book at once. I've always wondered who has the time to read and retain all of CLRS.
I haven't read these particular books but normally I have one "huge" CS book under progress at any time. It's usually a topic I want to know more about and get a basic fundamental understanding of, so mostly driven by the need for knowledge and the feeling that my knowledge is lacking in this area. That said, it usually takes me months to get through with one and often I already know some of the contents which I end up speed reading/skimming.