Boss Gangbanging

This technique utilizes the "strength in numbers" concept. Fighter-heavy parties especially will benefit from this. Since some bosses can only do damage to one player at once, or only one side of players, it can be useful to have all players attack at once. A cleric can heal the entire group at once, and due to the boss moving back and forth to attack each side of Fighters, the need to retreat will be lowered - damage will be more evenly spread amongst the mob of attacking players.

You have to read between the lines to get another hint you are suggesting: Have one group of players attack from the left and another attack from the right.