For ribs. I don't crutch ribs. The quality increase is small. In competition, you need all the help possible so you must crutch. If you are going to crutch ribs, be very careful that the bones don't puncture the foil. A double layer is recommended. People ask if they can put more than one slab in a package, but the effect will not be the same. You are essentially making a single thicker piece of meat and that will take longer to reach temp. Remember, thickness determines cooking time more than anything else. I don't recommend stacking.
On the rare occasion that I crutch ribs, I crutch for only 30 minutes. If you have heard of the 3-2-1 method, read the sidebar on the subject. I strongly disagree with the two hours in the crutch. Go much beyond 30 minutes and you risk overcooking the meat and turning it mushy.
You really can't tell when ribs are done with a thermometer. Click here to learn how to tell when ribs are ready. When the meat is ready you can paint on sauce, place it on a hot grill to caramelize the sugars, and serve. Click here to learn more about saucing strategies. If you wish, make Vermont Pig Candy with the liquid in the foil.