Well the way I heard it, the standard cooking times list for meat, like 20 minutes per pound for rare, were based on meats being warmer than the 40 degrees or less for meat kept in a refrigerator. Now I don’t know if that, or any of the other stories about room temperature meat are true, but I think it makes a difference for roasts and steaks to keep the outer part of the meat from getting overdone before the center is ready. This is more important if you like it rare, and you don’t want the meat cooked most of the way through before the center gets warmer than raw.
Now to cooking that roast. 2 or 3 days in the fridge isn’t really aging, but it does dry the meat which will improve the flavor and texture. After that, don’t marinade it, or put anything but salt and pepper on it.
For oven cooking: Put the roast on a rack in a hot oven to sear the meat, then lower the temp to 350 to let it roast. Don’t add any liquid to the pan, dry heat is best. Test with a thermometer, and when the temperature reaches 100deg its going to start cooking faster now. You can lower the temp to stretch the cooking time, leave it 350 until it’s done, or crank the heat up to 425 and pour your Yorkshire Pudding batter into the roasting pan. After about 15-20 minutes the pudding will be set and you can remove the roast if it’s done and let the pudding finish. Whenever you remove it, you want the temperature at least 10 degrees below the point where you want it done when you take it out of the oven. More so for a large roast. After it’s out of the oven, the temperature in the center will increase for a little while it sits. If you want it really rare, check the temperature with a thermometer after about 5 minutes, and put it back in the oven for a few minutes if the temperature isn’t at least 120.
For smoking: Smoked rib roast is unbelievably good. You definitely want to let it cook slowly, so let the meat get to room temperature before you start or it may never get done. Don’t sear the roast at all, just rub some salt and pepper on it, then warm smoke at around 200 degrees. For a large roast it may take 40 minutes per pound. Hickory, oak, and a little mesquite make good smoking flavors. If you don’t have a smoker, on a regular charcoal grill you can make a small fire on one side, and use a foil shield to keep the direct heat off the roast. You don’t need billowing smoke either, there’s plenty of cooking time for the aromatic flavors to soak into the meat.