Preheat oven to 250 degrees F.
Trim ducks: with a sharp knife, cut away excess fat and skin from both ends of ducks. (Render fat for another use or discard.)
Salt cavity of each duck. Prick each duck all over with a fork, about 30 times. Place them on a rack set in a large roasting pan and roast 1 hour. Prick ducks all over and turn on one side. Repeat pricking ducks all over and turn onto second side. Repeat two more times. After four hours, increase heat to 350 degrees F.
Continue to roast 30 to 90 minutes more, pricking and turning once, according to taste: 1) For very juicy, slightly crisp ducks: Roast 15 minutes, prick and turn, and roast 15 minutes more. 2) For juicy, crisp ducks: Roast 30 minutes, prick and turn, and roast 30 minutes more. 3) For slightly drier, very crisp ducks: Roast 45 minutes, prick and turn, and roast 45 minutes more.
Remove ducks to a carving board and let them sit 15 minutes, loosely covered. Simply cut ducks in half and serve half a duck per person; or carefully remove breast and legs from bone, making sure to keep skin intact, and cut them into 1/2-inch wide pieces. Generously season with salt and pepper before serving.