I frequently use the Search function and have found it very helpful; haven't tried advanced search yet. That being said, even if someone asks a question that's been asked several times before, there could be different responses than have already been given...new insights maybe, new ways of doing things. Just cause the question is "old" doesn't mean all the answers will be the same "old" answers!
One thing that kind of did annoy me a little was on a swap I'm involved in, posters kept asking the same questions over and over, instead of going to the first page and clicking on the link that had all the info.