Scoring 79 is difficult BUT possible! Many of our students have scored 79+ though they did not require that high points. But, if you score more, it'll benefit you more in your visa processing.
Well, you really need to practice hard. One thing you should remember is if you want to score high, you are paying an equal attention to all of the items in all the sections. This is because PTE's sections are interlinked. Say, 'Write from dictation' is not just listening. It's writing as well! Likewise 'Read aloud' is not just speaking, it's reading as well!
We have observed that more practice in newer material make candidate more confident. Aussizz' mock tests is the prime example. New questions, unique content, and thought-provoking passages train your brain in a better way making it ready for that beautiful figure of 79+.