XF 1.5 Deny access to single forum - User Group permissions

Just wanted to check that I have understood the concept of how permissions work. I wish to ban certain users from accessing our General discussion forum.

I have made a new User Group called 'No general discussion' and set all the permissions as the grey 'Not set (No)' column. I then don't touch the permissions for any forum/node except for General discussion' in which I set all permissions as the red 'Never' column.

I then leave any normal users in the standard Registered usergroup and add them as a secondary group to 'No general discussion.'

Is this correct?