It comes up time and again, one of the biggest drags in megadungeon play is the players mapping the place as they go. Often the time sink of mapping as they go leads to boredom, annoyance, and simply dropping the idea of mapping at all.
But mapping helps folks navigate the megadungeon, without the map some of the scale and scope of the place can be lost. With experience players and DMs will learn a shorthand that works for each other but not every player has the same grasp of language and how it relates to images or imagined reality.
As an exercise and example I present the "You are Here" sketch:
If there is no immediate threat to opening the door and poking your head into the room what is gained by describing the above without simply showing the above as a sketch?
Yes yuo can add to what's on the sketch with language but just imagine describing that all to the players and not boring someone at the table.
"You open the door into a fat roughly L shaped room with your enterance near the top left corner, up a short run of stairs across from you is a nook which seems to hold a statue. To your right there is a jutting section about 10' by 10' in the corner to your right, along the jutting wall section there is a sealed door in it's center, further along in that direction there is an overflowing gurgling fountain filling most of the area with a puddle of water, there appears to be a door in the far side from you along the short section of the L.The segment near you is 25 feet wide and the far section is just shy of 20 feet wide not counting the section with a door juttign into the room about 10', Overall the room is about 40 by 40."
Showing the art above with and elaboration of "You can't make out detail son the statue up the short stairs and the fountain gurgles as it slowly spills onto the floor." get's the job done.
Now I love hearing my own voice and quick use of language can be more flavorful than a quick sketch but one could use both in combination to greater effect.
These don't have to go onto a battlemat, or be laid out on a map by the DM but sketching problem rooms in advance can save a lot of table time.