Generally your hatch rates severely decline after more than a few weeks of refrigeration. Less so for long term cool counter storage.
But to the poster who said anything over ten days ..just throw it out? You can clean the brooders here when this batch hatches. There are seven dozen eggs, most older than two weeks, one dozen under, and three dozen that were over four weeks, and refrigerated or exposed to excessive heat.
Even have one about to hatch, wher first week the power failed for two days, got it going again and a power surge fried my thermostat and I got up to find my temps 113. The others died then or quit soon after. Thomas, the little orp who could is on day 19. He's doing fine as of this morning.
It's not over, until it's over. Many of my now developing hatch had free air cells due to shipping handling on top of the above conditions. The easiest way to fail is not to try.
Is it BEST to use fresh, well kept, gently handled eggs. You betcha. But NATURE herself is not kind. Brodie's have brains the size of peas. First time Broodies can be insane, lame, idiotic or worse. Nature makes poop, snow, ice, mud, rain, hail and disease, yet we have birds. Eggs are little miracle packages designed for variances common in nature and for challenges from it.
I've hatched healthy chicks from old, cold, muddy, hot, shaken and cracked eggs. Hatching is an art form. Drawing lines to make a coloring book helps people learn, but there IS art outside the lines. Nature is art. Life is art.
You can increase your odds but not past the point of luck. Even those huge hatcheries sometimes lose tens of thousands of "perfect eggs".
Playing with imperfection, means accepting that there is only so much you can do, and waiting on God to see if there is life in there. I actually like letting it roll on impossible eggs. They hatch or not, literally, God Willing. If I do my part and God does his/hers/theirs, voila, as close to a miracle as I am going to ever see in person.
Art and faith have much in common.
If it were a science, hatches would never fail for scientists.
Something else is going on. I happen to like being in touch with that.