Since I have a couple of metal detectors, and I have found hundreds of arrows with them I might have a warped idea of lighted nocks.
The detectors have taught me that you cannot bank on anything being visible on the arrow. My experience is that most of my own arrows shot from the ground and at Block targets on closely mowed ground will bury completely under the ground with field points., and this has been on dense packed sand. I do not remember an arrow in softer soil not being completely under the surface. I do find a few arrows not buried completely, but I couldn't begin to say what percentage of those were lost because the shooter didn't put eyes on them.
Because I use a scope on my crossbow I can always see if Bambi moves when I shoot. I have seen every single arrow go into Bambi, since I have yet to use one without a lighted nock in my crossbow. That information is very important to me. After the shot I follow through and if that light is centered in the scope know my arrow went where I wanted it to go. Shooting from well above ground means my arrows do not usually go completely under, but I have seen that happen on at least three occasions. On the single deer which the arrow did not penetrate all the way through the lit nock was spotted first in swamp grass when I was recovering the deer. That light is very, very useful to me. I wouldn't be without it. If for nothing else, going directly to the arrow after the shot and looking at the blood on it without wasting time and energy to find the arrow. For 15-20 grains of weight it's a no brainer, the cost is nothing when factored into the total cost of hunting deer.