Some years ago, few good 'Permissions workbooks' were circulating. I picked best one and modified it to make it a 'fully fledged' workbook giving a lot more relevant information about user permissions.
Workbook that gives 'User Permission' information: Views that shows:
1. Which user has 'what kind of access' to which site/project/workbook.
2. Users who have seen mentioned view/workbook
3. Users who have not seen any view
4. System users
Attached workbook has views for all the mentioned requirements. It taps into Tableau server's postgreSQL DB using 'readonly' user. I have developed the workbook using Tableau desktop 10.5
Enjoy. Connect with me if you face any difficulties.