Cooking a 7-pound pork shoulder in the oven takes about four to five hours, and cooking it in a slow cooker takes around 8 to 10 hours. Martha Stewart holds that a pork shoulder should be cooked until the meat is very tender.
Martha Stewart states that, to roast a pork shoulder, the meat should be seasoned with salt and pepper and placed fat-side up in a roasting pan with 1/2 cup water. Place it in a 450 degree oven for 45 minutes. Reduce the oven temperature to 350 degrees, cover the pan and allow the meat to cook for an additional four hours or until tender.