Being in a family of 2, I don't cook large pieces of meat very often. The typical pot roast I do will be no more than 3 pounds, which is plenty for a couple meals and leftovers for the 2 of us. However, I am having meat and potatoes lovers over for dinner and have a large 4.5 to 5 pound tied piece of chuck. Usually I would gently simmer the 3 pounder covered in a dutch oven on low for about 3 hours and it always comes out perfect. Should I increase the time for this big beast of a roast that I have? If so, how much? I know it will be technically cooked in 3 hours, but I want to ensure it will be tender.