Well I expect a mid to high band 5 for chemistry but I got a band 4, rip me lol. Other than that though the rest was more or less expected and I am satisfied with what I got even though it is not much compared to all the emperors on this forum.
If you are realistic with your goals and have worked consistently through the year then you should be able to accurately guess your bands for your subjects.
Personally i knew i would get Band 6 in Business, PDHPE and General and would definitely get a band 5 in English. For chemistry it was harder for me to guess as i had achieved mixed results throughout year 11 and 12