Thanks for the links.
Ive had my chickens for almost 6 months now and they are part of the family. We started off with 5 with various breeds, they got comfortable and after a month we started receiving 3+ eggs daily. We then decided to increase the flock with 5 more and all different breeds including a bantum chicken. They all varied in age and as such I have struggled to know what to feed them since some are pullets and the oldest bird being 8 months roughly. We have 10 chickens that have a nice coop which i built in the corner of the garden. I have about 25metres of grass and a small garden at the end and they roam free everyday as the gate is always open for them. There is one chicken that crokes in the morning when the gate is closed and thus we have adapted and leave them out everyday now. They produce 2-3 eggs per day, not enough to give away but enough for our family of 2 + 10 chickens. The important thing to note that even in my flock, the combination of these factors. A pecking order must be established thus creating stress on the initial 5 birds, then they get comfortable and we had another 5 so thus another pecking order needs to be established. The age of the birds varies and the right feed is important but hard to monitor. I have two isa browns and the rest are all different breeds, so 9 different breeds of chickens with different personalities and traits. The important thing to note when keeping chickens is the combination of all these factors not to mention water, conditions and weather. Imagine 10 chickens and 9 different breeds, i chose this on purpose as we treat them like our family. They are such great animals and family pets as they adapt to their surroundings. However i have come to terms with the fact that chickens are exactly as you have mentioned not machines. They co exist and are temperamental just like the rest of us. We also feed them scraps and all sorts of treats which we have observed that they enjoy, such as yogurt and bananas. Having 10 chickens and only 3 eggs per day does raise alarms to some but we have at least 3 chickens in that grey area of how old they exactly are and whether they are at laying periods yet. Ultimately they are very well looked after with plenty of food, water and great living conditions that they should produce each day however chickens are not machines that pop out a treat every time you invest a dollar. Patience and understanding is the key in my situation with the amount of breeds i have in my flock. Isa browns and leghorns are the ultimate egg laying breeds and i only have 2 chickens with such breeds the rest will vary greatly from bird to bird. Keeping all that in mind there is nothing your really doing wrong if your ticking all the boxes but it does not mean that you will get good egg production simply due to the breed, age and temperament of each bird.
If you are happy with your production, that's all that matters, but at this time of year you should be getting at least 50% of your birds of laying age laying daily.
As to the person who had a huge drop in production on birds just a year old, they may be going through a molt, which will stop egg laying until they are feathered out again.