That annoys the hell out of me and makes me less likely to reply. If you don't get a reply right away, that just means someone who knows the answer hasn't come along yet. All of the active posters drop in at least once a week, so you'll most likely get an answer within that time frame.
Be advised that if your question is about a new piece of gear that few people own or have used, you may wait longer than if it's a general question about technique or whatever.