I feel like there shouldn't be overtime if one team clears the checkpoint. With somewhat organized group you could just farm the opposing team on your side of the map until the last second and then just push at overtime to victory.
Overtime also should have some system that attempts to make the game end quickly during it, the worst i had was almost a 19 minute match. Hell, it could even be just the same effect that the Feast had with its increasing damage taken so overtimes would resolve rather quickly.