• I think you shouldn't hog the spotlight, but I don't know that "terse" is an absolute good. I think the goal is to provide players the right amount of vibe to riff off of--not so much they're bored, not so little that they can't grab onto anything.
• The Retired Adventurer's Encounter Grid system is a great tool for procedural pacing--basically, every roll of the encounter die yields a different trace of something on the encounter table, so players are always getting information about what's ahead, even if there' not encounters. It can be quite scary, too.
• I try to come up with One Good Bit for every major enemy and part of the dungeon. Generally an evocative ability tied to a sensory detail.
  • This monster is a trio of ghosts who play string games and conjure cursed thread to tangle up players. "As you swing your sword at the huddled figures, you realize a black thread is tied around your wrist. It's taught and leads off into the gloom, and suddenly, it pulls you."
  • "As you open the door, you notice a foul mineral smell, like stone if it could rot like meat."
  • "The woman turns and you realize she was a wolf all along, the curves of her body and clothes resolving into a massive beast like an optical illusion" (Particularly like this one because it's just a werewolf."
  • Even if it's something like an animal, you can talk about things like its hind claws raking the player's belly, it's hot breath in their face, ribbons on drool spooling on the ground. Think about how scary an animal attack is and dial in to what bothers you about it.

Even though other parts of the adventure or dungeon are typical, putting your creative effort into a handful of punchy details can carry a session.