AR Azure/O365 BackSync is disabled?

Is it required to have scheduled and running AR Sync Azure/O365 BackSync (GUIDs etc.) from AAD/O365 to onprem\AD objects (VAs) with AADConnect in place (AD/O365 Hybrid Mode)?

Is it supported scenario for AR by design?

IF AR BackSync Scheduled job is required THEN for which supported scenario:

1) Non Federated Domain (AADconnect is not configured)
2) Federated Domain (AADconnect and ADFS is configured)
3) Synchronized Identity Domain (AADconnect is configured)

(*) My customer got AR 7.4.3 with (3) Synchronized Identity Domain (AADconnect is configured) and AR BackSync jobs are disabled (not scheduled) at all, and it seems like there is no problem, so far.

thank you,

Aidar K.