My pleasure, Larry. Did you get an answer to your question about the Porterhouse Steak? It's a difficult one to grasp, and cook well, because of it's structure, a strip steak and a filet held together by bone. You may not really want to know, but i'll tell you anyway because it demonstrates the the thinking process you need to use before you cook it Medium-Rare.
Please consider that in SV cooking the Porterhouse its integral filet is just coming along for the swim. We know from experience the strip steak while being tender isn't the most tender steak so it should be cooked longer than the minimum time. How much longer? Well that's up to you using your best judgement or experience. If the meat is the usual grocery store product that's about the midpoint or 2 1/2 hours.
But that's not the exact midpoint, you say. Right, that's because it has that T-shaped bone that is more dense than the meat and the bone is going to restrict heat from diffusing evenly through the steak. Thus some more time will overcome the presence of the bone. Got it?
Remember using your experience to select an appropriate cooking time? Learning from your SV cooking experience becomes much easier if you keep a log or SV cooking journal recording all you cooks. Here's the SV cooking details i record.
Specific type or cut of meat.
Desired degree of doneness / cook temperature.
Thawed or frozen?
Planned / actual cook time.
Cook-serve / cook-chill / cook freeze?
Comments on outcome.
As you begin to gain experience your comments will be most useful because they will lead you to repeating a cook for that specific product or making a length of cooking time adjustment according to your results.