The zone system has its faults, such as anomalies with the boundaries, and a big jump in fares when you cross a zone boundary. But it’s one of the best things about Melbourne’s public transport. Its introduction in the 1980s led to a big boost in patronage, and in terms of ease of use, it remains the best way of charging for trips.
Where I live is walking distance to a zone 1 station, meaning I can do my usual commute to the CBD with a zone 1 ticket, saving over $500 per year compared to living in zone 2. That was part of the aim when I was house hunting.
But I’m actually in the zone overlap, thus while I can use zone 1 on the train into the city, almost any other trip requires a zone 2 ticket. Even the bus to Brighton (which is also in the overlap) curiously needs a zone 2 ticket — one of many anomalies with the boundaries.
While I could moan about that not being fair (and actually, I do from time to time), until they fix it, I figure it’s part of the cost of living on the outer-edge of zone 1. So beside my Yearly Z1 ticket, I have tucked in my wallet a 10×2 hour Z2 ticket for those trips (remembering that the Yearly is valid in both zones on weekends).
There are rules about when you can make a multi-zone trip on multiple tickets. Normally you need to have a single ticket for your trip, but if you hold a weekly or longer ticket, you can use a second “extension” ticket for the extra zone. If you can’t buy it beforehand (eg you are travelling from a location that sells only zone 1 tickets, into zone 2), you can buy the extra ticket at your destination.
[Source if you want to quote chapter and verse: Victorian Fares and Ticketing Manual 2008, chapter 11, page 94]