We have two license types for users within Salesforce:

    A. Time Tracker Users: They can track time for themselves and see their data
    B. Admin/Manager licenses are for people that need to do any of the following:

1. Set up users, configurations and other related work on the Time Tracker objects
2. Set up Task Assignments for their team members
3. Access time data for multiple users on their team
4. Modify (if needed) time entries for people on their team
5. Review and Approve time entries for people on their team
6. Get reports and dashboard access for all the members of their team

Generally, we find with most customers that there is a 1:10 or 1:20 ratio between Managers and Users.