I read somewhere that 4 trips equates to 1 journey on the Opal card, so the 5th trip you make will mean a new journey.
I went to experiment with this on my way home today for my last journey.
Trip 1: 6:05 bus ride - charged $2.10
Trip 2: 6:09 bus ride - charged $0
Trip 3: 6:18 bus ride - charged $0
Trip 4: 6:21 bus ride - charged $0
Trip 5: 6:52 train ride (10-20km) - charged $2.94
So I have been charged for the bus and the train, and the trick obviously hasn't worked! So where did I go wrong? Was I supposed to have taken 5 bus trips to make it 2 journeys? What does it mean if I then took 5 buses + 1 train, as opposed to 4 buses + 1 train? Does it only work on buses or is it 5 trips on any mode of transport?
What did you expect to happen? What exactly are you trying to ask?