Permissions are cumulative, so as long as you don't use Never, it will work.
There is no distinction between user and user group permissions.
Permission Value Priority
Each permission may be set to a different value. If a user is in multiple groups or has specific permissions set, this may cause multiple conflicting values for a permission. For example, a user may have both not set (no) and allow for the view node permission, so what takes priority?
Permission value priority is set in this order: (highest priority first)
Never – this will not grant the permission. This can never be overridden, so should be used sparingly.
Allow – this will grant the permission.
Not Set (No) – this will not grant the permission. This is the lowest priority value; any explicit allow will override this.
Thus, if a user has not set (no) and allow for a permission, the final value will be allow. The Test Permissions system can help confirm that permissions are set correctly.