There is nothing more annoying than being forced to fight trivial enemies one at a time for no logic other than that the game will not let you voluntarily fight more of them at once (cf., kobold dailies). The Sahagin quests were refreshing for not having this limitation; it was fun to come up with strategies to both increase efficiency and inject a modicum of strategy and challenge into these tasks.

Please think about whether this limitation is serving any legitimate purpose when implementing it in the future.