I use a Group (from the Group Management functionality) to enable permissions in a Workspace (and therefore all of the sheets, dashboards, and reports in the workspace).
However, in Workapps, we can not assign permissions to roles based on this Group. We have to enter users in individually. The screen capture shows the permission window from Workapps for reference.
When we need to make changes to a users permissions, we can not change the permission in one place. For example, if we need to delete a user's permission, we must do it in the Group and Workapp.