Some of us fill 'em up in the morning (and afternoon if necessary), and don't do any more than that. If they are outside, they will stop eating at night regardless, because it's dark and they're huddled-up. So, worst case, in the middle of summer, they're only going to sleep about 7 hours.
Out of my last batch of 150, I think I lost 5 after the age of 4 weeks. Others report better results with the 12/12 schedule, so I don't have anything against it, I'm just not sure that it has much effect unless you're raising them with lights 24/7, especially as we head into the Fall.
As for my Colored Rangers, I haven't lost any since the first couple days.