VMware/Physical: Continuously
Hyper-V: Every 30/300/900 seconds
Azure IaaS: Every 5 minutes
Details
VMware vSphere / Physical: In the Replication Policy an RPO threshold is configured. Alerts are generated when continuous replication exceeds this limit.
Hyper-V: In a Replication Policy the replication frequency can be configured to 30, 300 (default) and 900 seconds.
Azure IaaS: ASR creates crash-consistent recovery points every five minutes by default. This setting cannot be modified.