For chicken don't bother. Pork butts as a last resort to speeden a cook.
For ribs be careful, too long and you will have mushy ribs.
For larger tougher cuts of beef (brisket, chuck roast, etc.), foiling or braising is beneficial.
Foiling/braising means that the meat is cooking and steaming in it's own juices and any other liquid or flavors added to the foiled meat.
For beef at the time of foiling, adding complimentary flavors like red wine, minced garlic, onions, more rub should produce tender and flavorful results.
For ribs adding juices like pineapple and/or apple along with melted margarine and rub should produce good results.
Many participants of que competitions, foil both ribs and brisket.
John