Hi,
Here's my thoughts on maybe breaking this habit:
Know that constantly looking for traps or searching takes time and resources. You should hold that against the characters if they want to search every 5' section of the dungeon.
I don't know what ruleset you're using here, but if you're using 3.5, then taking 20 on a 5 foot square is 2 minutes. That's just the floor. Then there's the walls. So a 30 foot square chamber with a 10 foot high wall with one 10 foot wide exit would take approximately 2 hours. Sunrods are only good for six hours, a torch is good for an hour (or is it 30 min?) and so on. Light sources are going to wink out.
The second thing is that if the players are taking this much time, they are going to only explore about four or five rooms in a single eight hour day before they start pushing themselves. If you're dungeon is large enough, they should deplete their food and water as well.
The third thing is that if someone spends 2 hours in a single room in a dungeon, there should be random encounters or at least an encounter where monsters flee and go get reinforcements. If the PC's are raiding a lair and using the element of surprise to attack their opponents, the first room they decide to thoroughly search will give up that surprise and put the dungeon on alert. The more time the PC's spend searching, the more time the monsters will have to shore up their defenses, send out raiding parties, etc. A devious DM will have the monsters block the exits and trap the intruders once they realize that it's just a band of adventurers.
Another tactic is definitely the timed adventure. The longer the PC's dally, the higher the risk toward missing their goal.
Lastly, make the constant checking put on fast forward. Don't allow the players to roll for searching at every point. If they want to search the corridor ahead for traps and secret doors, simply state, "You search ahead and find nothing."