Since there seems to be a lot of discussion and theory about the hows and whys of hexcrawling in the OSR community recently, I'd figure I provide my take on the subject.
I use a method basically cribbed from the Wilderlands, a numbered hexmap with a key listing settlements, ruins, dungeons, lairs, monsters, weirdness, and so forth. Most of my entries are fairly brief, if I don't already have a vivid mental picture of what the situation is when the adventurers stumble upon it I usually improvise (I'm a big fan of improvisation in D&D), or I may arbitrarily dice for what's there.
I use the movement rates, encounter frequency and getting lost rules from the 1st ed. AD&D DMG. If you can see a landmark, or you have traveled the same ways previously, you probably won't get lost. With 5 mile hexes landmarks work out to be pretty reliable, aside from especially tortuous or preternatural terrain.
With 5 mile hexes I find that although they make for maps that cover a smaller geographic area that a mounted party can practically zip about and makes the existing campaign world feel small, this does facilitate quickie or spontaneous adventures. And I find 5 mile hexes a nice compromise between describing too small a geographic area versus a "more granular" world, although as has been pointed out, a 5 mile hex of wilderness is actually a big chunk of land that could easily require a lot of time searching in order to find a hidden crypt, a dragon's lair, a witch's hut, or even a village.
I don't mind that fact, some things on my map are there to be accidentally stumbled upon, others are fairly prominent, such as towers, pyramids, and giant monsters. Without really, thinking about it, I generally categorize the items in my wilderness key into three groups:
- Things that are meant to be found/seen, such as a glowing crystal tower or a sprawling ruined city in an open terrain hex. Most large settlements, which would have several trails and simple roads in the surrounding hex, fall in this category. I many cases you can see such features in neighboring or even further hexes. Some monsters in the key fall in this category.
- Things that have a fair chance to be found. Dungeons entrances, monster lairs, typical ruins, and so forth. Most monster encounters in my wilderness key call in this category. If an random encounter occurs in such a hex, I dice (50%/50%) to see if a such a hex feature is the encounter, or I may just make an arbitrary dice roll, "If I get a 5 or a 6 they stumble across the crashed rocket in this hex." Also, the party encounters the feature if I feel it is likely, appropriate, or if I just feel like it. If the party is actively searching, it takes time depending on the terrain and conditions, and unless someone makes an abysmally low dice roll, they find it and have to waste more time looking before another check is made.
- Hidden things. Buried assassin hideouts, buried treasure, buried cities, invisible strongholds, reclusive psychic hermits, and so forth. Maybe there's a 5 or 10% chance (or even higher, as this is supposed to be pulp swords & sorcery adventure after all!) that the party finds it or it occurs as a random encounter. If the party is searching for the feature I determine the specifics depending on the conditions. If they have a map and a guide that are both reliable, than they'll probablly just find it. If they're searching a mountain hex for an invisible hut without anything to go on, they better bring all the provender they can carry and establish a base camp and supply lines.
Basically, it works out to me generally playing it by ear, which is contrary to the procedural method implied in a lot of early D&D material, a method that I certainly find myself fetishing to a certain degree, but the free-wheeling method seems to work for my players and I.