These are two actions that can help ensure that the technician who performed a customer's initial installation is also assigned to subsequent service calls. A preferred resource is a resource that has a preference or affinity for working with a specific account or service territory. A preferred resource service objective is a service objective that prioritizes resources that are preferred for an account or service territory. By adding the technician as a preferred resource on the account record, and adding the preferred resource service objective to the scheduling policy, the system can assign the technician to future service appointments for that account.
References: https://help.salesforce.com/s/articleView?id=sf.fsl_preferred_resources.htm&type=5 https://help.
salesforce.com/s/articleView?id=sf.fsl_service_objectives.htm&type=5

Explanation
Customer Entitlements are records that specify customers' support terms based on their contracts or warranties[38]. Customer Entitlements can be used to offer appropriate appointment booking windows for Gold versus Standard Customers by defining different appointment windows for different entitlement levels[39]. Service Due Date is a field on the work order object that indicates when a work order must be completed by[40]. Customer Working Hours are records that define when customers are available for service appointments[41]. Service Urgency is a field on the work order object that indicates how quickly a work order must be completed[42]. References:
https://help.salesforce.com/s/articleView?id=sf.entitlements_overview.htm&type=5
https://help.salesforce.com/s/articleView?id=sf.fs_appointment_windows_entitlements.htm&type=5
https://help.salesforce.com/s/articleView?id=sf.fs_work_orders_fields.htm&type=5
https://help.salesforce.com/s/articleView?id=sf.fs_customer_working_hours_overview.htm&type=5
https://help.salesforce.com/s/articleView?id=sf.fs_work_orders_fields.htm&type=5