We were all taught to lead fourth from our longest and strongest suit against a no trump contract. The concept was that this would give us the best chance of knocking out their stoppers so that we could set up our suit. However, fourth from your longest and strongest is only correct in a vacuum where we have no other information, such as if they suddenly opened 3NT. However, in all auctions we do have information from both the auction and from what we hold in our hand. Instead of blindly following some rule given to beginners who cannot yet process this information, we should instead process all of the available information before we make a lead.