Player: “Ok, I’m going to move 30 here and use my sneak attack on the last- oh wait, I can’t, nevermind.”
Me: “Wait, why?”
Player: “He’s out of range by 5ft, I have disadvantage so no sneak attack.”
Me: “Bro just roll sneak attack, he’s the last goblin. We have cooler shit to get to this session.”
Player: “So, advantage?”
Me: “Yes advantage. Please don’t make me play one more round as this 7HP cannon fodder.”
If that goblin is the last enemy, it’s braver than any goblin on Toril.
Very few battles are fought to the last warrior. When the battle is basically over, enemies would know this and flee.