Well, I don't know what should be. I made some trials with entries in the GUI for Eye Depth and Light Depth and observed the values entered for Eye Depht increse inner reflexions whereas higher Light Depth than 5 did not have much of an effect on this scene, actually 3 is enough to get focused spots.
To proof what I observed there is a test running right now increasing value for Eye Depth starting with 3 and constant Light Depht of 3.
Who did know that one can animate these values with keys set with "I" (if mouse pointer is over entry field)
(But key bar is missing in Timeline window, not a big issue though.)