Fortimanager as Fortiguard server - SDWAN 6.4.7

Hi, What are the benefits of having Fortimanager to act as Fortiguard server for all the Fortigates which are in SDWAN fabric? . Fortimanager will be one of the DC LAN IP which has reachablity to all the branch Fortigate over SDWAN Fabric.

My observation

1 This will ensure that all database updates will happen locally within the fabric from Fortimanager to all Fortigates.

2 Not each fortigate needed internet connectivity..

3 Just ensure Fortimanager alone can speak with Fortiguard to get all the signature, database updates. Once this is done, it can push to rest of the device

4 It can also avoid impact to Webfiltering/Email filtering service, since any high latency from Fortigate to Fortigaurd webfilter service can cause "A rating error occured"

These are my observations, whether I am correct or any other benefits I have missed. Or anyother caveats in this setup.