The Hybrid Shared Services model makes use of a traditional hub & spoke Azure vNet design by leveraging a Shared Services environment in Azure and separate Prod & Non-Prod environments. Both Prod & Non-Prod can talk to Shared Services, but Prod & Non-Prod are completely isolated from one another.
From on-prem there's separate & isolated access to each of the 3 routing domains.
Redundancy is within region, leveraging the two separate ExpressRoute peering locations in Sydney.
Assign a higher weight to the local connection than to the remote connection
You can also influence routing from VNet to your on-premises network, if you have multiple ExpressRoute circuits, by configuring the weight of a connection instead of applying AS PATH prepending. For each prefix, we will always look at the connection weight before the AS Path length when deciding how to send traffic.