The more that you research BBQ, the more times you will see "magic numbers". We tend to keeps things simple and consistent when it comes to cooking temps. For instance, the most popular smoker temp for "low and slow" is 225. Hot & fast is either 275 or 325 (depends on your pit), although 325 is pretty common for pellet smokers.
Internal meat temps are also pretty basic: 135-145 for steaks, chops, roasts, and other "clean" meats, depending on your taste preferences. By clean meats, we mean that all of the bacteria is on the outsides, where it is cooked off. Today, even pork is considered safe at 140.
If the meat is ground such as burgers & sausages -- the dirty exterior is mixed in with the clean interior -- then go for 160-165. Ditto, all poultry needs to hit 160+ as well; birds have more bacteria than pork!
Your slow cooks, which require a lot of rendering & breaking down of collagen, such as brisket and pork shoulder, need to hit 195-210 -- with the magic number being 203.
It is extremely difficult to get an accurate meat temp on pork ribs, since there are a lot of bones and not much meat in between. We determine the doneness level of ribs by the bend test (Does the cooked rack almost break in half when you lift them?) and/or by just probing with a toothpick or your thermopen probe and feeling the amount of tension (should feel like you poked peanut butter).
Tel-Tru brand thermometers for measuring the air temp in the cooking chamber of grills/smokers are the "Sound Devices" of the cooking world.