It all depends on 'your' situation Ted. Some people have just enough birds that the natural decomposition can keep up with what the birds produce, and between them scratching and throwing dirt all over, especially when they find worms !! that they don't have to remove any of the bedding.
If it's rainy season and you are getting an inch of rain every day, then no it may take longer for you because everything is so wet. If it's winter and you live up north, then no, it won't work that way if everything is frozen.
From my experience I find that it takes about 4 weeks for the grass to get 'gone' via chicken pickin, the crap matting because the ground is still hard and packed grass roots not dug up yet. and the fly infestation because you got un 'being worked with' crap laying on packed grass, that the flies can get right into.-- to the point where the ground HAS been dug up, HAS been mixed with the pine shavings they also threw all over at this point, as they dug in there for bug goodies, the dirt HAS been dug a few inches deep so is now, loose and fluffy because it's being dug up and turned over and it's doing its thing
BECAUSE it is loose and getting 'new stuff' in it, it now attracts worms, who also eat left over food and chicken crap. The worms dig in from below. The worms attract chickens, who dig even further now, to find more worms, which also further mixes the stuff up, digs the hard stuff to soft mixed up stuff, deeper. soon you have 4 to 6 inches of nice worked compost, very loose, which lends to very good drainage, which also leads to very quick encapsulation of any new crap that hits it, .. it quickly surrounds it, the dust and dirt sticks, and it gets quickly mixed down into the rest of the composting compost. This keeps the smell to a minimum, and the flies are not really there anymore either.
It is very possible to reach a state of an equilibrium if you are not pushing the process harder than what it can naturally sustain, depending on your condition.
Another thing to consider. many people dig the compost out, not because they have to, because it's overflowing, but because they WANT IT. This stuff is black gold in gardens. I will rake mine once a month, to get the goodies, but leave just enough that it can still sustain itself, to continue the process.
if you have gone 3 years just adding stuff, then your process is already well going. Did you honestly think 3 years worth of poo would just sit there doing nothing? and NOT stink or turn into a 5 foot pile, without Something happening?
The fact that you are, or even sometimes HAVE to ADD to it shows that it is working. BTW worms will also take along with them, compost as well. If you ever had an oudside composter that was not an entirely enclosed container, you will notice that not only IN it is compost but the whole area around it probably for 4 to 5 feet is all soft, mixed up, super rich soil, because the worms carrying stuff with them OUT of the original contained area.
aaron