Can you explain to me how you would use it such that you could periodically harvest compost from Subpod for use in other areas in the garden?

Can you explain to me how you would use it such that you could periodically harvest compost from Subpod for use in other areas in the garden?

It will take around 17 to 22 weeks to convert organic waste to compost (for a full Subpod).  
So you could create compost for your other garden beds every 4-6 months. You can also plumb you Subpod to gain access to the worm juice, which is full of microbes and nutrients and spread this around to your garden beds. 
Lastly, If you would rather take the compost out of your Subpod sooner, you can simply use the internal divider wall in Subpod at any time. This allows you to stop feeding one section so the worms can migrate across to the other side. You can then scoop out your finished compost after 2 weeks - worm free- and begin the process again :)