Normally I wouldn't consider soaking them but I used some last weekend and I hardly got any smoke from my WSM, even though I put more than the normal amount of chunks in there. I think it may have had more to do with way the fire was lit. Instead of dumping 15 hot coals or on top of the basket, my buddy did a good half a chimney. Normally I sneak up on 250-275 over a half hour or so but it only took a couple minutes this time. I think things were just burning too fast to give me good smoke.
I guess the real lesson is here, if I have wood chunks laying around for that long, I'm not smoking enough. I have all kinds of stuff to use up. Guava, apple, cherry, mesquite, hickory, pecan... I better get at it.