Tips for condensing reading workload?

One of the biggest challenges that I have had since I started nursing school is decifering what is important vs. unimportant when reading the textbook. To fill you in on what I have noticed so far...my teachers do emphasize certain things in lectures and in their notes/ppts which is great and helpful, however sometimes there will be information on tests that covered things not mentioned in class or powerpoints. I do understand that they do want us to read the book and I definitely understand and respect the fact that they do not want to spoon feed us.However I have now tried to turn into some type of super-reader (which I am far from) and i find myself trying to read nearly every page and chapter that is assigned. My somewhat overachieving personality with studying and because teachers will pull questions from all over has me thinking things like, well I need to read that or this section, or that table/diagragm etc.,even though it was not mentioned in class or notes. I feel I will miss important information (I think I have a little OCD if you cant tell btw ha). Anyways I do get really bogged down and it takes me a really really long time to get through chapters. I feel like I am reading things that are unimportant and wasting a lot of time on information that is unnecessary related to the test. I end up of having to cram the night before a test just so i can read and understand all of the material. I think this approach effects my comprehension and has kind of effected my grades.

I was wondering if anyone could share what they do when reading the text. Are people like me and try to be big readers? What approaches have you taken to condense reading workload? How do you pick out important information vs unimportant information ? And any other study tips are greatly appreciated. Thanks !