Uh yeah... if you treat monsters with the same modicum of reality and sense that players treat their PCs.
If you are a orc band that got attacked by these interlopers and they then ran off after you defended yourself... you don't need to go chasing after them. You let them run off, and then you pack up your gear and head off for safer pastures. Why continue a fight that you don't need to get into?
The problem you bring up... to me is based upon a "gaming" mentality that many people have of not treating the monsters as actual thinking beings, but rather just mechanical doo-dads that act in accordance to the "game rules" and the "encounter". Our thinking of this being a "game" tells us that these monsters will keep attacking PCs until PCs are dead or they are... that they will continue following us like Jason Vorhees until we or they are dead, and that they will remain here in this spot even after the PCs have retreated in order to be "cleaned up" after the party rests and returns. The monsters aren't real... they are just gaming roadblocks the party has to get past.
If a DM wishes to run their game that way... that's cool, more power to them... but that's not a written part of the rules. Monsters do not have to chase you. And more often than not, probably shouldn't.