well all theories are going to have its flaws and errors. The short term phillips cruve doesn't work in the long term because there is a natural rate of unemployment. And the twin-deficit argument doesn't work because it assumes savings = investment which is never true.
I think you could actually discuss some of these flaws.....but if you're doing hsc economics, i don't suggest you go into much detail about that stuff cos it's not in the syllabus....if it's for your own knowledge then yeah go ahead.