Two enemy healers can out-sustain a single burst window - Fear/CC one healer away from the group before committing.
Nearly identical comp - the fight comes down to who lands the first big CC chain on the enemy's primary healer.
Both sides run the same burst-and-heal shell - whoever's CC chain lands on the enemy's main healer first usually decides it.
Your burst outpaces their DoT plan - press the advantage early rather than settling into a long attrition fight.