If you can't finish a game, don't play one
I'm sick and tired of getting into games where at ten minutes someone says "I gotta go soon." Why the hell did you play? Seriously league isn't and never should be a game where you can just shoot through matches like confetti. If you know for a fact that you would not be able to finish a game, no matter how long you think it would take, don't join a match. I don't care if it's ranked, norms, twisted treeline, or URF, you are ruining the game for everyone on your team.