Why is it better to roast prime rib as a double chop as opposed to a singular or triple?
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When roasting a single chop is going to over cook fairly quickly. A double chop is the minimum I would try. Don't know why a triple would not be acceptable.
Prime rib is normally served medium rare with a nice crust on the exterior. This is difficut to do with a smaller roast. As already mentioned above, it will over cook and a exterior crust will not be formed. If you like your meat (gasp) well done, it may not make a difference; but you will be wasting a good cut of meat...