I agree Scotty, if I use foil at all, one hour tops, for loin backs. Spare ribs may be able to handle a bit more time, but anything mor than 1 1/2 hours and I start to worry about having a pile of bones with mushy meat.
Truth be told, I haven't used foil on the last three rib cooks I have done and I really feel they have been some of the best I've cooked.
Treasurer, Great Lakes BBQAssociation
Rubbed, Smoked, and Sauced Competition BBQ Team-
22 1/2" WSM, 2 18 1/2" WSM's, 22 1/2" Weber Kettle