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.”
5e combat is so mindless and numb that it doesn’t hurt to simply call combat when it’s pretty clear that an encounter is going to end one way but over multiple, slow, agonisingly boring rounds. Better yet, incorporate morale checks from older editions.