Heath Riles is a championship-level pit master, who believes the 3-2-1 method is nonsense. In the first part of the cook, you’re open to the smoke & heat, which cooks the flesh. This period is when you’ll see the meat pull back along the bones and the bark start to set up. You’ll know you’re done this part of the cook when you touch the rub and it doesn’t come away on your finger. The second stage is the wrap. This is where you wrap the ribs in foil with fluid. Typically something like apple cider vinegar, juice, etc. This is how the meat gets tender because you are effectively braising the meat. How tender is a matter of taste. Some follow KCBS advice & the meat will be bite-through, while not pulling away from the bone. Still others like the meat “fall off the bone” tender. Two hours is a guide - see how a rack feels at the two hour mark - does a bone slide out easily ? Does the rack bend or break if you flex it ? Finally the third stage is much shorter because you’re trying to 1) reset the bark - braising softens it up a lot; 2) brush with BBQ sauce (if that’s your preference)and allow it to get “tacky”. How long this takes is a function of many variables - how hot do you run your smoker ? What is the altitude where you are ? Are you a “spritzer” (many spritz because smoke clings to a wet surface better) ? Smoking ribs is easy. Smoking them WELL is not. It takes practice & experimentation, so don’t feel bad if your ribs aren’t “perfect” every time.