Web designer Container (iteration), how can I create a HTML parent container for every third element?

In Web Designer, I have a Container (Iteration) node and I'm getting all of the items from the container without issue but the format it's showing is not how I want it. There is a tick box in the Container (Iteration) node that is "Do not create a HTML parent container". I've tested with this ticked and unticked and the behaviour I'm looking for is somewhere between these two extremes. I want a HTML parent container to be created after each 3 elements in the iteration. Is there a way I can do this?