Creating a report using the Case Snapshot report type is a reporting solution that can help the manager compare the amount of time that cases have spent within each status during their lifecycle. The Case Snapshot report type shows the case status and the number of days that the case was in each status. The Case Snapshot report type can help identify bottlenecks and inefficiencies in the case resolution process. Verified References: : https://help.salesforce.com/s/articleView?id=sf.reports_standard_report_types.htm&type=5 :
https://help.salesforce.com/s/articleView?id=sf.reports_case_snapshot.htm&type=5

Explanation
Milestones can be added to work orders, cases, and entitlements in Salesforce. Work orders are records that track service requests for customers. Cases are records that track customer issues or inquiries. Entitlements are units of customer support that specify what kind of support a customer is eligible for. You can use milestones to define the required steps and time limits for resolving work orders, cases, and entitlements. Verified References: Milestones: Supported Objects

To prevent duplicate customer contact information, the recommended approach is to configure and activate Salesforce's built-in Duplicate Management feature. This feature allows for the creation of duplicate rules and matching rules to identify and prevent duplicates at the point of entry. It can be applied to standard objects like Contacts and can provide users with alerts or block duplicates based on the rules set. This proactive approach ensures data quality without requiring excessive manual intervention or extensive access rights like "View All Data."