[sblock]I get the impression that it might help if I step away from mechanical analysis and tell you what this might look like in play, since you seem to be under the misconception that this is somehow a problem that is not easily solved.
[sblock=Gameplay]
So, we have a stereotypical Party of Four. They meet at a tavern, and the shady old guy in the corner tells them that if they recover the MacGuffin that the goblins stole from him, they will be fabulously rewarded. The party goes up to the entrance to the goblin warren.
So, lets say the goblin warren has 4 goblin warriors (1 challenge for each character for Combat), 4 traps (1 challenge for each character for Exploration), and 4 kobold slaves (1 challenge for each character for Interaction: they can be turned into allies!). There's other noncombat goblins in the warren as well -- the warrens are, after all, the goblin's lair. Each goblin has 5 hp. Very simple.
Each character has a "Basic Skill" in each pillar. Basic Fighting (deals 1 hp of damage), Basic Exploring, Basic Talking. This comes from your background.
Fighters get a Power Attack ability they can use whenever they want to deal +3 damage on any attack. Rogues have the Broad Skills ability that gives them a +1 bonus to all their basic skills. Clerics have three spells: Cure Light Wounds, Find Traps, and Divination. Wizards have three spells: Acid Arrow, Knock, and Charm Person. These are vancian spells: single-use, prepared in advance.
So the party wants to get into the warren and get the MacGuffin and get back out. They meet a goblin standing guard, and the spellcasters want to to show off because they assume that as spellcasters they are the only ones necessary in the adventure. The wizard goes in with Charm Person on the goblin. It fails. The goblin gets to attack, pricks the wizard, and the wizard uses an Acid Arrow. Because the Acid Arrow is 5 x the power of a basic ability, it kills the goblin. Blarg. The cleric then heals the wizard. To prepare, the cleric uses Divination to find out what will happen when they go through the front door, and finds out that there's a trap on the other side of the door. So the cleric uses Find Traps to locate the trap, and uses the thief's Basic Exploration skill (5 checks) to try to disarm it.
So, the party has dealt with 1 goblin and 1 trap (out of 4 each), and has used up all of their spells. A "nova" by any definition of the term.
Because the spellcasters assume they are the only important members of the party, they say, "Hey, lets rest now, there's probably more than one goblin in there." They go back to town, and rest at the inn. The fighter calls them pansies.
While they do that, the goblins discover that their sentry is dead, his face melted off by acid. They say, "We've been found!" Now they "recharge." Possible options include:
- Make your kobold slaves build traps through the night. They can build two traps. This adds two more traps, bringing the total smerp challenge to 5 traps, 3 goblins, and 4 kobold slaves.
- Grab the wolves that've been hanging out near the larder. They tie them down near the entrance and poke them with sticks. This adds two more combat encounters, and brings the smerp to 3 traps, 3 goblins, 4 kobold slaves, and two really angry wolves.
- Ask a noncombat messenger to run over to the next hill and tell the goblin king that they've been attacked. Two more goblins show up by morning, and brings the smerp to 5 goblins, 3 traps, 4 kobold slaves.
- Activate the MacGuffin, which summons and binds a demon into servitude. The demon is an elite creature. This brings the total to 3 goblins, 1 elite demon, 4 kobold slaves, and 3 traps.
- Give eight of the noncombatants swords and put them at the entrance. They are minions. This brings the total to 3 goblins, 8 minions, 4 kobold slaves, and 3 traps.
- Uproot everyone and go to the Backup Lair, where they have a buddy and a few traps already there ready. This brings the total back to 4 goblins, 4 traps, and 4 kobold slaves.
...or really whatever else the DM can imagine. Eight hours or so is not a trivial amount of time.
Now the party comes back the next day, and they're facing...pretty much the same situation they were facing the night before, mechanically. The adventure has recharged, just as the party has.
[/sblock]
The party retreats. The threat recharges. It makes sense in context in a million different ways in a thousand different contexts. No matter what, the nova is not necessarily a winning strategy (though it is a strategy that may change the dynamic -- some of those options locate more in the Combat pillar or more in the Exploration pillar than before...hope that wizard prepares more Acid Arrows...and the demon or the wolves might turn into an Interaction challenge if the party wants to offer some souls or has a druid or something). There are more challenges present than spells can solve.
Does that help dispel your notion that somehow a recharging adventure is absurd or implausible?
If not, I can probably do the same thing for almost any scenario you can derive. I bet you can, too.[/sblock]