@djuntgen thanks for the suggestion. I went ahead and updated the documentation. Since my last response to this thread in August, the polling frequency has been updated to every 500ms.
The trigger methods don't using a polling mechanism. The microcontroller on the ambient module triggers an interrupt on the third GPIO pin on the module port which causes Tessel to fetch the value that triggered the interrupt as soon as possible (pending an opening in the event queue).
Hope that makes it a little more clear!