A Single Collector can work across multiple RG's (Resource Groups) within Azure. What is needed is network access to the Source technologies.
The exception is when doing private networking in each of the resource groups, and in that case they would need to have a collector per private VNet, or Vnet Peering setup so that the collector can communicate to all private resources.
In a Multi-Region deployment, having a collector deployed in each region is best-practice.
Updated about 4 years ago