Interesting! If that's so, then is it possible to roughly determine that a hen laying considerably lighter eggs than she did at first (cream coloured rather than dark honey) would be about ready to stop laying and begin her moult cycle?
And that her flock-mates who are still laying darker brown eggs are not quite as far along (even though they're the same age)?
I have 12 ISA Brown hens who have been laying very well since the end of July and it's now February. I get 10-12 eggs every morning, but a couple of them are creamy rather than the much darker mottled brown the rest lay.
Nobody's shedding any feathers though. Hopefully they'll wait until winter breaks a bit before losing their insulation!