Wandering Monsters

Wandering monsters are a poor substitute for using actual plot to motivate PCs to take risks and bravely explore a dangerous area despite depleted resources during an adventure.

The intent of using wandering monsters is to add excitement to the adventure by forcing the PCs to press on for as long as they can before they run out of resources.  The motivation to press on comes from the danger that, during the rest, there is a chance that they will be attacked by a random monster.

I've already got a beef.  Random monsters don't advance the story. You're putting off your story for an hour just to make the players feel some time pressure?  You can do better than that.

Now, I define taking a risk in a tabletop RPG as making "a consequential decision based on incomplete information."  This is because of the interactive, socially-constructed nature of the imagined world.  Let's look at that decision...

• Consequence:  We know that the consequence is a random encounter from the random encounter tables.  Those encounters are usually not too hard.  Much like any other encounter, they vary from fairly easy to challenging, but they're never "boss fight" tough.  In other words, they're as tough as any other regular encounter.  Therefore to prepare for the consequence, adventurers need to rest when they have enough "fuel" left to do one more encounter.  That's the dominant strategy, at least.
• Information:  While the players don't know that they will have an encounter if they rest, they know how much gas they need in their tank to handle a typical encounter.  They generally have a very good idea how many resources they need to conserve to survive one encounter (hit points, spells, Daily attack powers, etc. -- pick your edition). 

The PCs' degree of caution or bravery will color these decisions.  Cautious characters may want more than an encounter worth of resources (they may stock scrolls and potions and wands).  Brave characters may be willing to press on until they're on their last hit point.  Both fit in almost any fantasy subgenre. 

What the players' characters decide is none of your business.  

Otherwise, the risk-based decision making that wandering monsters puts on players is about as exciting as when to stop for gas on a road trip.  How many miles to the next gas station?  Not exciting.  

Now what if you use plot instead of wandering monsters?  Adding plot instead of diluting it sounds like a good idea to me.  Plus, wandering monsters get overdone -- every dungeon has wandering monsters?  That's going to get old.  

Here's an example of wandering monsters vs. plot.

We’re exploring the cave system looking for the legendary Talisman of Ioun.  Wandering monsters sent by the lich Rakzadul might attack us, so we can’t just rest arbitrarily.

• Light on Consequence:  A combat encounter might waste our time, but give us XP.
• Heavy on Information:  We know how many more combat encounters we can handle so we can make sure we're prepared just in case.

We’re exploring the cave system looking for the legendary Talisman of Ioun.  In two days’ time, the shadow moon will be full and the lich Rakzadul will destroy the talisman in a dark ritual of apotheosis.

• Heavy on Consequence:  Rakzadul destroys the talisman and could become an evil god.
• Light on Information:  We have no idea how many encounters are left be before we find the talisman.

There are other advantages of using plot, too.  It doesn't involve looking up tables or involving an additional sub-system.  It doesn't bring in the XP and treasure systems.  It adds story instead of delaying it.  I could go on!

Four word summary:  Use plot, not tables.