Well, I'd say that there is always more to learn - even if you feel you are proficient in Australian politics, you won't be familiar with every aspect of it. Picking a subject that you know well and like can be great, if you make sure that you are extending your knowledge, rather than just rehashing things you already know.
I have to say that, in retrospect, I would have liked a little more variety in the subject areas that I chose. I suppose it's just a question of whether good marks or new ideas are more important to you. (Keeping in mind that it is possible to do well in arts courses that you aren't familiar with, given that they mostly revolve around essay writing skills which are reasonably transferable across government/sociology/philosophy etc).
I have to say that, in retrospect, I would have liked a little more variety in the subject areas that I chose. I suppose it's just a question of whether good marks or new ideas are more important to you. (Keeping in mind that it is possible to do well in arts courses that you aren't familiar with, given that they mostly revolve around essay writing skills which are reasonably transferable across government/sociology/philosophy etc).