Campaign Durations

Thinking of how long my campaigns have lasted... Just the post-2000 campaigns. Here's what I can recall of tabletop campaigns I've GM'd:

Gaxmoor (3e D&D): 2000-2003; 3 years.
Barakus (3e D&D): 2004-2006, 2 years.
Willow Vale (3e D&D): 2008-10, 2 years with gaps.
Larin Karr (4e D&D): 2009-10, 18 months with gaps. 18 sessions?
Southlands (4e D&D): 2010-11, 6 months. 20 sessions.
Loudwater (4e D&D): 2011-2016, ongoing, 5 years, 94 sessions so far.
Yggsburgh (Pathfinder Beginner Box): ca 2012, ca 6 months, 12 sessions.
Punjar Saga (4e D&D): 2013, ca 6 months, ca 12 sessions.
Crimson Throne (Pathfinder): 2014-15, 2 years, 34 sessions.
Karameikos (Classic D&D): early 2015-, ongoing.
Varisia (5e D&D): late 2015-, ongoing, 12 sessions so far.

Hexploration

It looks pretty empty, but they're only 1 mile hexes. DMG says a half dozen monster lairs across 50 miles. This is about 30x40 miles.

You can definitely have more than 6 monster lairs in a 50x50 = 2500 square mile area. 
6 monster lairs in a 50 square mile area (5 x 10 miles) seems high but not outlandish 
especially if they're man-sized or smaller; it mostly depends on what they eat and what the food 
supply is like. A big dragon might have a 900 square mile (30x30) or more hunting range,
but most creatures will have much smaller ranges. Hunter-gatherer humans & similar man-sized humanoids likely have a density between about 1/sq mile (though much lower in extreme desert) to 10/sq mile (very fertile areas like the Pacific Northwest of N America). Mixed herder/hunter types 
will have a higher density; Small creatures like Goblins can be much higher, for 3' tall 
creartures 8 times as many, while Large creatures like Ogres will be much lower - a creature weighing 5 humans will likely need 5 times the hunting range. Farmer density goes from about 10/sq mile in barren areas like the Scottish Highlands to 100/sq mile and above, medieval France 118/sq mile, can be much higher with intensive rice-paddy agriculture.

I used 1 mile/hex maps in my Yggsburgh game, based off Gygax's 1 mile/hex map in 
that book, which covered a 50x50 mile area. That works really well for getting to know 
an area in depth, which makes sense for settlement/colonisation. Gygax has a campaign's worth of monster lairs and dungeons in that area. 
Doing a new map every 2-3 adventuring days seems excessive, at the very most I'd do 1 map
per Tier. Eg you could do a 1 mile/hex map for levels 1-4, 3 miles/hex for levels 5-10, 
10 miles/hex for levels 11-16, and 30 miles/hex continental map for levels 17-20.

Read more: http://www.enworld.org/forum/showthread.php?478910-Hexcrawls-wilderness-adventures/page6#ixzz42ImcocBT