It probably depends on how interested you are in the subject matter. I loved reading the Homeworld manual, mainly the section of ship stats. Or way back in elementary school, Isaac Asimov had some short books in his Library of the Universe collection, books on the planets. My favorite part of those was the Fact Sheet at the back, that was just charts of data about each planet. Diameter, orbital period, composition, # of moons, and so on. My 4th grade teacher gave me a perfect score for the section on the planets because I knew the material better than her. I had those books damn near memorized.
But switch to my Project Management for Engineers course last semester. Oh god.....that textbook did literally put me to sleep twice. I don't think I read more than 10 pages of it the entire semester.
Fortunately, that class didn't really require much effort, or much more than 50 functioning brain cells. There was ONE formal homework assignment the entire semester. The other work consisted of a program called SimProject, where we had to hire imaginary people and allocate them to imaginary tasks for an imaginary project. It wasn't especially detailed. Each person had sets of "stats" about their performance. I wrote an efficiency-evaluator spreadsheet, and determined who would give the best performance for the cost. 
My group was #1 in the class, up until we discovered a fun "feature" of the software. When hiring people, clicking "Hire Resource" queues the hiring until you click "Submit Decisions," which sends all completed decisions to the server for processing. However, when you click "Fire Resource," it takes place immediately, and those resources can't be hired back for two more periods. This was discovered after those resources were fired.
So we fell down to #5 in a single period, since our imaginary project team had suddenly lost more than half of its members.
Besides that, there was a semester-long project. It was a lot of mindless writing and busywork. At least that was my perception of it.
I got an A- in the class, probably because my cumulative time spent prepping for the tests, including the final, was less than an hour.