I've always bought the weekly passes if I'm in Sydney more than 4 days. It's pretty easy to get around on your own with bus, rail and ferry. I'll frequently see the Sydney Explorer buses park right next to the bus I'm getting on or off. You do need to take some time to sort out what routing to take. I remember my first trip to Bondi Beach I took the bus all the way out from Circular Quay, as I didn't know it was easier to train to Bondi and then take the bus from there to Bondi Beach.