Well, that's USyd all right.
Speaking of fucking shit, law's fucking shit, and I wish I didn't go down this path.
I decided im taking it during semester
If you're interested in speeding up your progression through your course, you could overload. However, it can be quite intense, especially in units with load of labs (e.g., biomedical units, chemistry units). Mathematics, physics, and geoscience kids can probably overload comfortable if they can manage the coursework and additional problems/practice.
the number of subjects offered in summer school is quite limited though
from what I can remember, only the popular ones are offered , like math1001 , maths2061 etc
That is, classes worth running.
check out
http://sydney.edu.au/summer/ for subjects offered some time next month
but I don't think it's worth it even if it's offered
Per
http://www.maths.usyd.edu.au/u/UG/SS/SS1004/r/2013info1004.pdf, it appears that it has run previously, albeit by a then few-months-old Ph.D. student (but also an IMO guy and a Medallist).
Per
http://www.maths.usyd.edu.au/u/UG/SS/SS1004/, it appears that it will run again for the 2014 SS.
TBH, if you're not in a hurry to finish units or won't overload, you probably are better off doing it in-semester. However, if this means messing your TT and graduating later than you would, maybe it's better that you do it during SS.
May I ask why you considered taking this in SS? Being proactive? Repeating a subject?