Mike L. I spent 5 summers guiding out of Ketchikan and 6 out of Craig and can count on 1 hand how many times I anchored. There are quite a few guys that do anchor up for butts around Ketchikan and I actually think that it is probably more productive if your targeting larger fish, but I rarely had to target them and didn't like to hassle with the whole anchoring process.
On the west side of P.O.W. Is. (Craig area) there are few if any guys that anchor for halibut, I don't really know why it hasn't caught on there other then most of fishing is done on open water with alot of various species of fish available and it just seems more productive to cover water rather then sit on anchor, there are alot of areas that in 1 half-mile drift you can put kings, silvers, butts and lings in the box in 1 drift, did that on a regular basis.
Another factor is that most of the halibut grounds (that I fished anyways) were pushing 180-200 ft deep.
Lastly, there doesn't seem to be many charters around Craig that target big butts, some (me included) promote releasing the really big ones, like I mentioned earlier, if I were looking for big fish I might anchor but I really don't see much need to go through the hassle when the halibut fishing is as easy as it is just drifting.