Dungeon Exploration is much more about how you choose to play the game then any rules.
Take two groups:
Group A. The game here sort of starts at 6pm and most players will show up before 8 pm or so. It's a relaxed fun atmosphere and everyone sits around, tells jokes, watches You tube videos and goofs off. Maybe, sometime before 8 pm someone will mention "hey lets play a little D&D game". The group will sort of start gaming for a couple minutes, then everyone sits around, tells jokes, watches You Tube videos and goofs off. And game a bit and goof off a lot. And even while gaming the pace is slow. The players are random and disorganized and just sort of have thier characters stumble through the vague game world. Most of the players don't know the rules and game information. Worse the game has to be stopped 17 times when a player complains about something and the DM wants to "talk about it". So doing even two rooms in a dungeon exploration can take an hour.
Group Z. The game starts at 6pm. Players that don't make it, don't play. All the good players are there by 5:30. The game starts with full deep role playing immersion. Should a player waste even a few seconds of game time goofing off, they will be sent home. Each player if focused on role play acting out their character. All the players know all the rules they need too. Any player asking a dumb rule question will simply be sent home. The players role play act a lot like a tactical squad raiding an area. They clear rooms and move through the dungeon with speed and grace. No player complains about anything during the game. And other then Breaks, the DM will never pause the game to talk. So whole dungeon levels can be gone through in an hour.