I agree with Bardsandsages, and that was part of the point I was trying to make as well. There are more people who don't have an exit plan, than do in real life, and in most games. Case in point, few PCs have an actual exit plan for every fight. To qualify as an exit plan, means to plan how to get away BEFORE the fight starts.
Coming up with a good strategy using the elements at hand when you find yourself losing, is quick thinking, but does NOT constitute an exit plan. This is in effect, and ad-hoc exit plan.
Still, in all of this, comareddin is bringing up an important concept, in order to provide realistic opponents to PCs, the DM needs to have NPCs do more than fight until dead.
I think NPCs should have basic reactions to losing:
1) fight until death
2) use a pre-planned exit strategy
3) run away/hide
4) escape using whatever the current situation provides
I think the NPCs actual course of action (based on the above choices) is based on the INT of the NPC, type of NPC, resources available to the NPC, and the situation at hand.
For NPCs of high INT, the DM may need to always plan an exit strategy (while presenting it as if it were #4) to simulate the high intelligence of the BBEG. This may be considered using meta-game knowledge to simulate a smarter than the DM character.
One could even argue that for each encounter, the DM should decide which choice the NPC would use, and play the combat to that choice. This means the DM is deliberately varying the NPC response, providing a more "realistic" experience. Compare this to most new DM's choosing choice #1 by default for every monster in the dungeon.
In the spirit of the actual thread topic, here's an encounter with an exit plan:
NPCs plan an ambush along a wooded trail.
If they are reduced to 75% in number then
they delay their action to be on the same init # (in case they had differing inits)
run randomly into the woods, weaving amongst the trees to provide cover
they will hide for about an hour
they will all regroup at a landmark they agreed upon earlier, before trailing the PCs or returning to base
The purpose of this is to provide guerilla tactics against the party, preserving the lives of the NPCs. Their job is to harass and weaken the party, other encounters farther along the trail will continue the job. They have no practical means to run ahead of the party to attack them again, though they may decide to follow discreetly and eventually catch up and rear attack the party during some other encounter. The NPCs could be a monster race (like goblins) and simulate a random encounter, or they could be part of a larger plan.
In this case, the PCs should only get XP for the NPCs killed/captured, because full combat was never part of the NPCs plan (by "routing" the enemy, the PCs have not actually defeated the NPCs, because it was their plan to run away after light losses). This is different than direct confrontation with some monsters or a BBEG, where running away was a decision made at the last minute. In that case, the PCs have effectively defeated the enemy (and his plan to kill the PCs).
My intention with the above encounter is to provide a generic strategy template for a typical "group of bad guys attack the PCs in the woods". Not every encounter should be like this, but a PC trek to the local bandits' hideout could very well include a few encounters like this.
