If you use quality wood, there's no need to soak them. Hardware store/WalMart wood is usually too dry, so a soak or foil wrap will help those from combusting. With good wood (SI hickory or cherry, Fruitawood, Maine Grilling Wood), you shouldn't have any combustion, and they smoke great. The idea is to get the smoke going as soon as possible, since your meat will only really "absorb" the smoke until it reaches about 140 internal temp. After that, it just builds up on the surface and makes it bitter. No reason to "prolong" the smoke...it you soak it, it has to dry in the box long enough to start smoldering.