It's not about healing less, it's about using your healing efficiently and working with your co-healer for their O-GCDs. You use maths to max uptime your DPS and heal based on the level of damage and mitigation planning with your crew, you got Regen stuff too use them to their advantage. Melees have Feint, Casters have Addle, Ranged have Samba (etc), Tanks have multiple mitigation tools, work with them to reduce incoming damage and allowing you to push DPS more. Getting a fight over quicker results less mistakes in the long run.