We have a hub and spoke design in Azure for our vNets and needed to peer the vNets together. This can be done in an ARM template and we could have deployed all three networks in one go and peered them as part of the ARM template deployment. For various reasons that approach didn’t really work for us, 1 reason was the customer is very sensitive to change control and having all 3 vNets being controlled by one ARM deployment didn’t sit very well with them and made them nervous.