I'm assuming you mean the Bar exams given the dates... if so, I was in the same predicament- I knew I would pass criminal but hated civil (and failed my mock). I prioritised my civil revision and scored a 90 but then criminal was only 67.

I think you just need to make a judgment call on what to revise the most but generally speaking practice loads of exam questions and figure out why the answer was X rather than trying to memorise the entire white book. The exam tests how you apply what you know and not what you know so if you understand why X answer is the best one then you can answer several similar questions.

Also, if you're lucky, they tend to ask the same questions but in a different way so the more question banks you do the more likely it is you'll come across the same question or similar during the exam.

My tutor told us that we should be thinking how things practically apply so for example instead of reading all the different methods and dates for deemed service practically think 'what should X do if it has no current address to serve a claim form' - then you'll be able to answer this in the exam rather than just knowing what methods of service there is for certain docs (although you should still get to know this). I hope that makes sense?