From what I found lighting helps all birds in the winter. It depends on the breed of bird. A buckeye will not lay any more in the winter than in the summer neither will a welsummer from my experience without lighting. From what I found, If the bird lays lots of eggs in the summer she will lay lots of eggs in the winter with lighting. This includes if the weather is in the negative numbers.. This is just what I have noticed.
I cannot help you with identifying birds that are slackers as last spring and this fall I thought I sold my slackers but they were the best layers and now I have a majority of slackers in my coop. Other than my pullets that are laying the majority of eggs.
Bee knows how to identify the slackers!!!!!!! Though her technique may not be for the faint of heart, lol lol lol