You, the DM, have prepared a dungeon at once naive and ironic, located as it is atop a beetle-browed eminence called Skull Mountain for all the right reasons. You've prepared wilderness hexes covering all reasonable approaches to the mountain and the adjacent hexes, populating them with a mixture of rolls from the Fiend Folio outdoors tables (but replacing Carbuncle with Centaurs; cmon, a carbuncle?) and a few odd features from the Wilderness Alphabet.
The party starts 20 miles to the south in a frontier town called Ygrvale. The Ygrevalians tell of ongoing skirmish wars 'twixt them centaurs an' them haffalings an' them gobbalings and bugbears in the hills to the north. A slight detour takes you through clearer terrain to the east, though. Maybe the locals tell you about the green dragon who lives in the woods just by the detour. Maybe they don't, because the dragon lets them skip the yearly maiden sacrifice if they send him some people with bags full of money and magic items every now and then. The dragon is in league with nearby bandits, who guard his lair while he sleeps in return for being allowed to live.
(It's just this working out of relationships ahead of time that explains why I like this method, compared to random rolls on a table.)
Off you set, your laden mule and footborne henchmen giving you a rate of 9 (90'). We'll say that you can use 3 of those points to enter a plains hex (light green), 5 going through hills, 6 for forest and all 9 to climb the mountain. Advanced maps might have trails, or routes of easier going marked out by landmarks, that take fewer movement points.
Head straight for the skull, or detour right or left? The party decides on a bee-line, so they can get to the center of the first hex and most of the way to the center of the next, going through hills.
- Morning encounter roll at the crack of dawn (hour 1, rolled on d6), still in the Ygrvale hex, is a 13; nothing.
- Hex entry roll, the bugbear hex, is an 8. Potential encounter from 2 hexes away. The d12 comes up 4. Uh oh - two hexes due east is the green dragon, and the dragon has range 2 and flies by day, so it's an encounter. The party finds the dragon dining on freshly chlorinated goat. Luckily, the dragon is amenable to fast talking, and lets the party march on having paid tribute of one mule, a quiver of magic arrows, and a sackful of gold.
- Afternoon roll at hour 4, trekking through the bugbear hex, comes up 3. Bugbears? Nope, it's still day.
- Second hex entry roll comes up 20 - roll twice! 4 and 15, centered on the new hex. No encounter, twice.
- The party camps for the night and the DM makes two static rolls. First watch rolls a 5, followed by a d6 and a direction of 3. That would be a wight ... if he wasn't stuck in his lair. Second watch comes up 9, which would be a clue except the party isn't moving and there's nothing in the hex to leave a clue.
- Morning breaks, Skull Mountain looms in the distance and the party continues north. The morning roll is a 1 (empty hex).
- Hex entry roll for the second empty hex is an 11, clue to adjacent hex ... it's a 5, the centaur hex ... the party sees, over on the next hilltop, a huge twig and wicker effigy of a centaur, brandishing a spear menacingly at the Skull Mountain.
- Afternoon roll is a 1 again, and they're at the foothills of Skull Mountain.
Coming back, the party agrees to steer clear of the dragon's woods, now they have some real capital gains to be extorted. They decide on a slight detour through the more heavily populated (unknown to them) row of hexes heading down on the west. To make things short:
The first day is uneventful, the silence of the night only broken by the loud sound of centaurs mating somewhere over a hill crest (rolling a 9, you let them have another clue to the centaur hex even though they're not moving, it helps build the ambiance of the hills).
The second day and night pass absolutely without incident, the night camp just north of the mountain lion hex.
The third day's hex entry roll is a 1; they've found the mountain lion's lair with an angry lioness defending three cubs! A henchman is mauled, but the lioness is finally slain; the ranger captures one of the cubs as the others scatter, and takes the mother's pelt in lieu of treasure. The DM crosses off d2 from the mountain lion hex and write in "1" - there's going to be a male mountain lion out for revenge in the hills ...
The only encounter left in the day is a 2 rolled on entering the Ygrvale hex, a patrol from the town that seems amazed to see the party alive at all... And they're sleeping on a down mattress tonight.
Of course, a real killer DM who played monsters to the hilt would have the green dragon get savvy to where the party were going, and trail them to the Skull using every ounce of its guile and spellcraft, for a chance at some of the real loot.