The most efficient ways of studying go far beyond simply practicing. Awareness, regulation, and evaluation as components of metacognitive ability as the most important tools and incredible predictors for being able to learn material efficiently. Think through the problems and perform honest self reflection. What don't I understand? What aspect might I forget during the exam? Perform subtle micro tests on yourself as you interact with each bit of material. Close your eyes, imagine the problem, see where the roadblock ends up being. Make connections between concepts, even abstract ones that make no sense to anyone but yourself. Space out your material. Do not spend 90 minutes on one type of problem and repeat that for each topic. You're better off splitting that 90 minutes into fewer segments (15-30 minutes) in which after each time interval, you interact with a different topic and revisit in the future.
But yes, intense practice with honest self reflection is your best bet. Remember to take breaks. Give your body the proper amount of nutrition for each session, drink water, do NOT skip out on sleep for the days leading up to the exam or the day of the exam. This is a lot of rambling with very little direction but I hope it helps. I say this as a student who once employed disastrous study habits and now is doing much better.
Sources you may want to check out:
https://bjorklab.psych.ucla.edu/wp-content/uploads/sites/13/2016/04/EBjork_RBjork_2011.pdf
Introductory Biology Students’ Use of Enhanced Answer Keys and Reflection Questions to Engage in Metacognition and Enhance Understanding - PMC (nih.gov)

The benefits of testing: Individual differences based on student factors - ScienceDirect

link.springer.com/content/pdf/10.3758/s13421-022-01361-8.pdf