cluster controller does audio of all jobs first, then video, instead of completing first job then moving to next

Hi,

I'm using the cluster controller to queue up multiple projects. I've just 
queued up 4 and told it to start, and it seems to be doing the audio for 
each project first instead of completing all tasks in the first project, 
then moving to the next.

Just wondering if I can change it from one behaviour to the other 
somewhere?