I did not do so well on the HESI that we took half-way through the program - we had been told not to worry about studying for it, just go take it, not such great advice as it turns out! So for the exit HESI, I did study, but not a ton. What I did more than anything was a ton of practice questions from a variety of sources. I used our textbook, Saunder's, the LaCharity "Prioritization, Delegation..." book of practice questions, questions from the study guide for our text, and the HESI NCLEX prep book (used to be a HESI prep book until HESI was bought out by Evolve - this one is good because it gives review material if you want it but the questions are all on disc and are the same format as the actual HESI - helps with test anxiety!).
Now I didn't do every question in every one of these sources, not by a long shot. Mostly because I want to save them for NCLEX studying
Over the course of a few days before the HESI, I did probably about 300 questions. I don't know if that sounds like a lot or a little, but trust me, it was a little. And it was painful because I got a LOT of them wrong. But going over the rationales is what really made a big difference for me on the HESI (which I rocked). I learned a ton, and it was across the board so I got a little smattering of a lot of different disease processes. I read rationales for the ones I got wrong but also for the ones I got right, so I could make sure I really understood the content of the question. Many questions led me to look things up and investigate a little more, so that's how review of the material got worked into the process. It seemed like the best way to make the most of a little study time. There was still plenty on the HESI I didn't know, but the way it's scored you can miss a bunch and still do well. It gave me great insight for how I will strategize studying for the NCLEX.
Another important point is that the non-textbook study guides all have some sort of test-taking strategy information in them. That info is very, very useful. Many times even if you don't know the right answer to a question, you can deduce it using test-taking strategies. That helped me so much. Even if I ended up getting some of those questions wrong, it kept my confidence up during the exam, I didn't freak out when faced with a question where I had no idea because I still had ways to narrow it down to feel confidence in an answer. (If you're going to get a question wrong anyway, it's better to at least *feel* like you got it right! That way you have more confidence when the next question pops up.)
Final note, if you do study this way, do NOT freak out if you find that you are missing a lot of the practice questions! As long as you are following up with the rationales, then it's information that you've learned and that you'll know for the exam.
Good luck! You are trending in the right direction, you can do this!