To limit subscriber records by BU based on the 'Region' profile attribute, Northern Trail Outfitters should select 'Define Subscriber Filter' for each BU on the BU Setup page and configure a condition to match the corresponding profile attribute. This will allow users who are assigned to a BU to only view and send to subscribers who have the same region value as their BU. References: https://help.salesforce.com/s
/articleView?id=sf.mc_co_business_unit_setup.htm&type=5

To provide near real-time data in a 30-day welcome journey, Northern Trail Outfitters should use contact data using synchronized data sources. This will allow them to access the most up-to-date data from their CRM system in decision splits and other journey activities. Journey data is static and based on the entry source data extension, which may not reflect recent changes in CRM. Contact data mapped through profile attributes or imported from CRM reports may not be as timely or accurate as synchronized data sources. References:
https://help.salesforce.com/s/articleView?id=sf.mc_co_synchronized_data_sources.htm&type=5 https://help.
salesforce.com/s/articleView?id=sf.mc_jb_decision_split.htm&type=5