Hi 

I suggest you have more disk groups per node, to have greater redundancy in case of a disk failure. If you use only one diskgroup in the event of a disk failure you would lose the diskgroup of that node and therefore all the space of the node. If, on the other hand, you use more diskgroups per node, the failure of a disk only impacts on a diskgroup and therefore only on part of the node's disks. You also have performance gains.

These are somewhat old but interesting links:

vSAN Failure Scenarios - Virtual Blocks Blog (vmware.com)

One versus multiple VSAN disk groups per host | Yellow Bricks (yellow-bricks.com)