The best way to balance the amount of assets scanned by each scanning server when using Active Directory Domain scanning is to make use of the OU filters. If you add an OU filters to an Active Directory scanning target only the specified OUs and any sub-OUs contained within are scanned.
If you assets are all in one big single OU, we would recommend you divide your assets up into a few OUs and then use the OU filters to divide the OUs amongst your scanning servers. More information about scanning with an Active Directory Domain scanning target can be found in this knowledgebase article: https://www.lansweeper.com/kb/130/scanning-with-active-scanning.html
