I just took my Advanced Med/Surg ATI this past Wednesday. We are converting to ATI from HESI at my college. I have taken both.
I would say if you are doing well in the class you should do well on the exam. I was passing my Advanced Med/Surg course and had our final exam on Tuesday before the ATI. My brain wouldn't let me study before ATI on Tuesday night, I had been hitting my Iggy Med/Surg book pretty hard for the past 3 weeks for the final.
I also made flashcards with Patho, signs/symptoms, diagnosis & lab tests, & nursing interventions on them for diseases. I only use one side of the card. I used the larger flashcards, small ones don't have the room for all that info, I like the fact you could take flash cards anywhere and if your board you can just look at them and you can even take pics for your phone to look at.
I looked over some of the conditions/diseases I thought were harder for me to understand, I also watched videos (YouTube) on the subjects that I couldn't grasp so well.
I would make a note of what medications your ATI book has listed, they seemed to be different than our class book, the names were different but the drug classes weren't.
Look over your syllabus to see what you should cover and be sure to know about everything thing in your syllabus because usually they don't test on subjects not covered.
I only read the ATI Med/Surg book to study for the ATI exam & I used Iggy, our recommended Adv. Med/Surg & Med/Surg book for our class exams because our instructor read out of the book in class, & she would read the book for our test questions when we reviewed our exams.
In my class, we had to have a passing grade to be able to take our ATI a second time & we had to have a level 2 to pass the class.
I am happy to say I passed my class & ATI on the first try with a level 2.
Good Luck to you!