Dungeons are just spaces like forests and the streets of Neverwinter, encounters occur in these spaces on a regular basis depending on the location which varies greatly.

For example, moving on the high road during the day there is a 1 in 20 chance per hour to have something happen and that something can include an encounter of various severities. It increases on a tributary road and changes for off-road. Say on road, you have a chance of being ambushed which can be tricky even if you're wary and watching. If you're in the forest you won't be ambushed, as no one expects you to be there, but you could be stalked or stumbled upon by something and that's roughly the same chance but has varying consequences and scenarios.

So resting just off the road vs resting in an open field is about the same chance of danger. Resting in a hidden location in the forest is 50% less dangerous (1 in 30 per hour).

Moving off-road with stealth is 50% less dangerous.
Moving while covering your trail will prevent stalking
Moving slowly is similar to stealth but will take longer and therefore increase the number of rolls per mile traveled, you must be proficient in stealth to move with stealth and cover your trail otherwise you just move with stealth.

The math is set to favor moving with stealth while covering your trail but while moving slowly decreases the encounters per hour it is a wash for encounters per mile. Without proficiency, moving with stealth is about the same as moving slowly and the speed is similar as well if you have proficiency your speed can be normal with stealth and counter-tracking.

Camp fires will ward against creatures but draw bandits to you so it will change the encounter type but it will also dramatically increase the danger of bandit attack if they're in the area because of the light, smoke, smell etc. Intelligent and tame creatures typically are drawn to the fire, wild creatures are discouraged.

Dungeons:
For every level down (roughly) the danger increases by 1/20th.

So if surface is 1 in 20 chance of an encounter per hour, level 1 would be 2 in 20 chance, level 2 would be 3 in 20 chance, and so on.

It would be then wise not to rest unless absolutely necessary. You can limit the chances by barakading yourself in a small room, especially one you had to pick to enter and was undisturbed, like a crypt. Versus a rat's nest would expect to have some occupants return.

SheShe's run currently has them on level 2 of a dungeon and they need to rest. They just defeated two 400XP encounters back to back and need to rest. They run a risk of triggering another encounter and it could be worse since their party is at a point that they could handle even more so the decision to rest now vs getting to the next room that might be a good spot or have allies is the trade off. 

Since movement in a dungeon doesn't take hours usually, there's no worry about an hourly roll, instead most encounters are triggered by room rules. Rooms don't always contain enemies, and friendlies can be very helpful to the careful adventurer. Even evil groups can be helpful, especially lawful evil ones. Evil creatures can be allied with temporarily though they do tend to let their nature out eventually.

In SheShe's run, they encountered Kobolds (lawful evil) who needed something from them and gave them a quest. Bear held this over their head and they allowed them to rest under their protection. However, resting without a watch would have been unwise as even lawful evil characters will take advantage of situations. 

So be careful out there.