Single or Multiple Protection group?

Hi,

I have Site A and Site B with Vcenter and SRM , My Question is regarding Protection Groups , I have 4 TB LUN which will have 20 Vms and Replication will be based on Storage replication (Array)  I understand that in Storage replication All VMs will be fail over at same time,  What is recommended to have 1 protection groups for all VMs or Multiple Protection groups.

Regards

Usman