I've learned the hard way that if I-as-DM don't have a map I'm hooped; as if I wing it I'll inevitably end up putting two rooms in the same physical space, which the players - using their map - will gleefully (and rightly!) point out.I hope not because I often don't have a map.
There are occasions where I will use one, like a large dungeon complex that I expect them to be in for a few sessions. For something where it might only be a single session and they get in and out then I will often not worry about a map.I've learned the hard way that if I-as-DM don't have a map I'm hooped; as if I wing it I'll inevitably end up putting two rooms in the same physical space, which the players - using their map - will gleefully (and rightly!) point out.

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.