Tracking time in the dungeon

One of the things that still gives me a little bit of difficulty when I’m DMing is tracking time in the game’s fiction when the characters are in exploration mode. Combat is simple, the 6 second rounds are codified, and we know that 10 rounds is a minute in the game world, 5 rounds is just :30 seconds, and so on. Which means most fights are resolved in just under :20 seconds! Wow! 

Social encounters are also fairly easy to determine, as it’s usually real time conversations, with perhaps some minor adjudications of time passing as you negotiate and wait around for the car salesman to go talk to his manager about the offer you made him, etc… 

But inside the dungeon, as the players are exploring, that’s a whole different…eh… monster. Now, the game offers a bit of rules in that regard… the DMG tells us that PCs moving…