You need to think from examiners point of views first!!
Unlike other subject ISCA is pure theory with no laws, so if you try to interpret in your language & you are missing main crux chances of getting zero is high.
I assume for more examiners also it is diffcult to justify the anser which deviate from module language.
Also in ISCA what you assume about Question is asked about is not actually the Question asked, so read Question 2 to 3 times before attempting so that you know in detail whether it is features/characteristics you need to define.
According to me in ISCA study less but study 100% with very good grip on terms.
Try to copy paste module language only.
Highlight key points in answer only if you are 100% sure about it.
Dont buff around if you dont know about it.
If yo are not good in understanding of system interace then atleast 4-5 you need to revised the subject.
All the best & god bless to all.