Dungeon Delving

[AsheItachi]

So I have a group who is started going into dungeons. Im using roll20 to run this game and I like to give them free reign movement over exploring. Im trying to dissuade them from saying I take 20 on everything and I actively walk around this huge dungeon with constant perception rolls.
Note that I dont not want them to find the traps I just dont want them acting like they should get a standard action roll if there near one. I do roll reactionary for them if they aren't focused on perception.

Im not tyring to rob them of anything I just dont want them trying to min max dungeon crawling I want it to be a real experience.

Any tips or advice from GMs who have done alot of crawls and how to keep it flowing instead of every 30 feet them rolling perceptions and castin detect magic to find the magic items easy.

[Surpriser]

One very important thing is to place traps where they would be reasonable and not just randomly. If every 10ft section of nondescript dungeon walls can contain traps, expect the players to search every single nondescript 10ft section of walls for traps.
Instead, place traps in natural locations: At (obvious) chokepoints, important portals and access point, in the treasure chamber and so on. This will reward clever players for searching for traps at the right moments.

In addition, introduce time constraints of some sort: Have the inhabitants of the dungeon act intelligently. If the PCs take 5 minutes to traverse a corridor, these are 5 minutes more for their enemies to set up defenses and call for reinforcements. Make sure to let your players become aware of this: "The barricade in front of the door looks like it was just assembled hastily within the last few minutes. Seems like you could have surprised them while building it if only you had been a bit faster..."
One other thing to discourage taking a disproportional amount of time can be random monsters or regular patrouilles.