Due to a number of factors my primary playing group tends to take very cautious approach to gaming when I DM. The reason for this is likely that I don't tend to pull any punches, and generally enjoy challenging them by giving them difficult situations.
That being said, over time it has made them extremely wary of my dungeons, traps, and in general anything. They are typically exhaustive in searching rooms, doing checks and in general being safe. Mind you there is the occasional stint of excellent RP (when the klepto mage saw something shiny and just grabbed it). This does however cause me problems because I typically have to be even more elaborate with my next set of challenges which causes them to be more cautious.
This has also forced me to have to be very clear and decisive in some situations (such as declaring when they enter the room that "there is nothing interesting in this room and they can move on"). Otherwise we waste hours searching empty rooms that were just meant as filler.
How can I get my players to play a little more dangerously and spend less time worried about being prepared and more time enjoying the content? I would prefer to not have to scale down the encounters (too much) if possible.