Prior to both my biol exams; like the few days leading up to it i probs only did around 1-2 hours a day. Just re-read, re-summarised, and went over past vcaa exams and analysed the style of answers that examiners want by reading the examiners report. on the day before both exams i did nothing, just chilled out and took it easy.
For history i practically did hardly any work 4-5 days prior to the exam. i was just doing a few questions (which only take 10 minutes) here and there. And i did plenty of reading, which i already did as a pastime since i love history so much.
I got plenty of sleep before each exam. But then again i've never tried to pull all nighters etc before SACS and exams. Throughout this year i always had a policy where i vowed to stop all work at 10pm and go to sleep by 11-11:30. Closer to exams i might have studied to 10:30, but not often as i didnt feel i required any more time.
Overall i'd say the key to avoiding disasters is keep up and staying prepared, and furthermore, continually studying and reviewing. By constantly reviewing material i was able to still achieve a 25/25 for one Biol SAC that i had completely forgot about as i was too busy worrying about a Revs SAC, simply because throughout the semester i would review material each week, do soem checkpoints, exam questions etc. so that i was never forced to cram towards the exam when things started to get a bit more stressfull.
I got 44 for both my subjects