Gronan, if the players were making their way out of the dungeon, retracing their steps by following their own map, which we'll assume is accurate enough, how much would Gary abbreviate the journey, if at all? Would he call out every ten feet as if they were exploring? Would he just say, "Yeah, that map gets you out from here" and skip to their arrival in town? Was there some method in between these extremes that he used?
Greyhawk was FULL of indetectable sloping passages, teleporters, shifting sections of wall, and one way doors. If you ever got out exactly the same way you got in it was a minor miracle.
Also don't forget you can't map during pursuit, and we ran A LOT.
Heh, that reminds me of a conversation I had with Rob Kuntz once about PCs using wishes to bump up their ability scores. He said that usually didn't happen because the smart PCs used to save their wishes to get out of the dungeon after they became hopelessly lost.