Explanation
With a hybrid migration, you can migrate the mailboxes in small batches over a period of time which will help to avoid saturating the bandwidth. With the migration wizard, you can configure a migration batch to start outside office hours which would minimize bandwidth usage during office hours.
With a hybrid migration, you do not need to reconfigure Outlook to connect to the migrated mailbox. Outlook will automatically detect the new mailbox location. This reduces administrative effort.
Reference:
https://docs.microsoft.com/en-us/exchange/mailbox-migration/mailbox-migration