I was waiting for someone to bring up humans...
If I have twin daughters, and they're both cared for the same way their entire lives, they are very unlikely to begin puberty on the exact same day, though it's likely they can menstruate simultaneously each month (as it's been exhibited in human females that if they spend a lot of time together, their cycles will correlate). But if one of my daughter's moves away, this won't work anymore. And even still, it's highly unlikely they will both hit menopause at the exact same time.
This 'exact' science thing just isn't true. Each chicken and each human has different genetics even in a case of twins, unless the twins are identical and EVEN STILL, it's impossible for these reproductive egg laying things to happen as an exact measurable scientific activity being the same for every flock mate or birth mate.
This is my opinion and the theory interests me, I just believe it is to be not plausable.