Not so sure about that although it's commonly quoted.
For instance the Libs/Labor only need an extra half quota to get another seat. In WA last election I think the Libs had half a quota left before they went to preferences.
I think Libs or Labor winning 4 quotas in a half-Senate election is virtually impossible, but there is a chance of winning 7 quotas in a full-Senate election.
As the veritable Antony Green keeps saying - forget about it anyway. It won't happen.
