Well yes, you are correct. It is easy to pass Newstep to get into automatic entry courses that are popular - nursing, teaching etc... but if you are aiming for something higher, you really do have to work. The highest score you can achieve is 93. Think of the people aiming for subjects in the late 80's.Be warned that from my experience, many of the students simply didn't belong there and were more suited to back of a high school English fundamentals class. However, it is really not hard to go well in Newstep, most of the content is easy, force fed and basically any monkey that can operate MS word will receive distinctions.
I don't know if they still have it, but there was an open research course (I forget the exact name). It is a complete waste of time. You sit there for 2 hours doing nothing 11 of 12 weeks. Only pursue if you're passionate about researching something for the sake of it.
Try pick something relevant to your degree of interest too, especially if you aren't adequently endowed with the knowledge from high school (eg: maths for any science/engineering/maths degree, biology for any science degree).