Virgin always seems to carry high connections around its network.
Last year on a delayed MEL-OOL we needed to wait while 30 people got off quickly to connect to the OOL-DPS flight.
DPS directs on Virgin can often get pricey especially in peak while connections are cheaper. Having a look next at the June School Hols, I can connect via Sydney for cheaper on many of the days. You get a huge number of connections when the holiday periods across states don’t align also, ie the directs from Melbourne might be full or priced out for many, but NSW is a week ahead or behind in holidays, so the Sydney connection is priced well and it fills up.