Thank you for getting back to me.
I have forgotten to mention that with this property you will not see parent nodes expanded if a page is bellow the max data bind depth. Other considerations you might want to check out would be to set pages not to be shown in navigation if you do not want them loaded in navigation controls. This can be set from a page's properties tab (see image). If you have a very big Site Map the best approach for using optimized navigation control would be using Site Tree View control and enabling it to use Load on Demand - more information on how to enable it in this demo
If you have more questions, please feel free to contact us.
the Telerik team