I'm an old hand at brining: no turkey cooked in my house for the last couple of decades has escaped brining prior to cooking, for instance.
Brining does indeed yield more juicy results. However, if you are used to dry and stringy white meat on poultry, or dry pork, you are overcooking. Brining will help, but it will not cure this problem. If, for instance, you brine a turkey, then cook it until the temperature thingie pops up, it will be a bit juicier than it would be if you hadn't brined. The problem is that the thingie pops up about twenty degrees too late. Cook your bird to 165 degrees, instead of 185 degrees, and the difference will astonish you, brined or not.
If you brine, then cook to temperature, as opposed to time, you will be amazed at the results you will achieve.
The same goes for pork. Pork only needs to be cooked to 150 degrees, but most people cook it WAY over that, and then wonder why it is dry. Sure, a pork roast that is brined and then cooked to 190 will be juicier than one that is not brined and cooked to the same temperature, but one that is brined, cooked to 150, then allowed to rest will be heavenly.
And that is another problem a lot of people have. They cook a turkey, or a pork roast, scramble to make sure everything else is done when the main meat comes out of the oven, and then immediately plunk it down on the table and begin carving. And everyone exclaims "Look how juicy it is!" as they watch the juice that should stay in the meat run onto the carving board, or plate, or whatever.
But, I don't wish to belittle the effects of brining. By all means, brine your turkey, your pork, your chicken. It is very easy to do, and has amazing benefits. Shellfish, shrimp especially, also benefit from brining. If you wish to turn out plump, juicy, and tender shrimp, brine it for a half-hour or so before you cook it.
But if brining has suddenly rescued you from dry, chewy and stringy white meat, you should try brining and then cooking to temperature. As I said, you'll be amazed at the results.