Great North Walk

Hi I am relatively new to hiking and would appreciate feedback. I am planning to walk the GNW starting from Sydney. I am Planning to do short trips over weekends with a friend. We have done the Six foot Track, the Coastal Walk in Roayal National Park and a few sections of the GNW in the Berowra National Park. We just completed the section from Hornsby to Mt Kuringai and although a beautiful walk the track at times was difficult to follow due to overgrown vegetation and fallen trees. I am familiar with this area and new where we were going, but is a little nervous once veering into the Brisbane Waters National Park. Is it common for the hiking trails to be so overgrown on GNW?
Feedback would be appreciated!
Keen to learn!
Feedback would be appreciated!
Keen to learn!