Guy are you aging them after you breast them skin on or whole birds fresh from the hunt...then breasting them?
I do age them whole, back down, on news paper...I got a man refrigerator in the garage just for it ...
Closely watch temp, like to keep right at 37 but don't want it to freeze. They will age like this fine up to 2 weeks. I have gone longer, but they start to discolor after 2 weeks, but never had a duck gone bad, your nose is your friend.
I age whole just for convenience. My preference is to breast them after after the hunt, clean very good, get feathers off, clean blood clots out... And I give a good rinse with water, run water till it goes clear... I used to soak in water for days, brine (as can be seen in 2nd pic), I think all that is worthless I don't mess with that any more and I think you are better off not doing it. I put breast in a big tupperware, where it can lay flat and breast are not stack on each other, so it can breath... Season, normally just salt and pepper. I put paper towel in there, to soak up excess juice, but not so much it goes dry, but stays moist, and even marinades in its own seasoned blood juice, but not too much juice. I give the breast a flip every day, and every day you can tell a difference in the texture of the meat. It goes from a rubbery texture to more of texture of a steak you buy at the store. I think aging helps with the puckering, but I have yet to find a formula to eliminate it.