Yes, thats what I calculated also, 2 shipments per week for Wunma or 1 large cargo vessel per week, if things are going well there should be another shipment this month.
I've been tracking the large cargo vessel since it pulled up stumps a couple of days ago, its only now just leaving the gulf, its just north of NT but still under the tip of QLD at the time of this post.
It seems to be moving at about 20 to 25km /hr, so pretty slow so it probably takes a week or so to reach China, assuming thats where its headed.
In about another 100k's it will be in shipping lanes and be too difficult to track, without paying the website or knowing the correct name of the vessel, as in the hours that I would sleep it would move too far to identify it accurately amongst the other vessels the next day.