Interesting chart but there in Nesbit, MS - it may not be as sad a scenario as up here near the 49th parallel. The failing hours of daylight drop like a stage curtain every year.
Growing with decreasing hours of light suppresses development. I turned on a light in the coop when the hours of darkness totaled more than the hours of daylight last Fall. Then, slowly added a few hours. Without a light, by late December, the birds would have been spending about 16 hours on the roost in the dark and the cold.
Still, I like to get my chicks as late as possible in the Spring. They aren't outdoors at first but cool, windy, wet weather certainly isn't as healthy for them as warm Summer days.
The opposite of suppressed development is also the case with too many daylight hours, as I understand it. Controlling light is important for the commercial outfits and they will limit hours of light so that young birds aren't rushed to maturity.
Steve