Ive been looking for an older network of the cable trams, but very hard to find (As there were some differing routes)
but I did come across this map of the track currently in the CBD
Swanston St is the world's busiest tram route (from the Arts Centre at the bottom of the map) to Melbourne University - #1, #3 (and 3a), #5, #6, #8, #16, #64, #67 and #72 - each route runs on anywhere from 8-12 minute off peak frequencies, about 6-8 minutes in peak so there's an insance frequency on that 2km stretch. The link between Swanston St and Elizabeth St does not have regular services, primarily used for transferring rolling stock between the two segments.
(note lack of grand union junctions)