These are two aspects that a consultant should consider for migrating Territory Management to a new structure for the upcoming fiscal year. Territories can inherit assignment rules from other territories higher in the model, which can simplify the process of assigning accounts and users to multiple territories. Only one territory model can be active at any given time, which means that you need to deactivate the current model before activating the new one, and ensure that there is no gap in territory coverage. Verified Reference:
https://developer.salesforce.com/resources2/certification-site/files/SGCertifiedSalesCloudConsultant.pdf (page 22)
https://help.salesforce.com/s/articleView?id=sf.customize_territories.htm&type=5