I've never had any problems tanking these first 3 groups even with undergeared or terrible healers (like that SCH who just spams physic even when you're almost full HP) since ShB early access (which means bad gear). If at least half of the mobs die faster than the tank goes out of CDs it's easy as hell. All tanks have tools to survive with little to no healing required in these situations, it just requires an average tank that uses its job's tools and average DPS from all four players in the party. If you struggle healing and find yourself unable to DPS it's most likely the tank being a bad tank not using mitigation and/or self-healing tools or bad overall DPS making the fight way too long (a healer dealing 0 damage can definitely lead to that if the DPS are just average). Or sometimes both if you're unlucky.

And as almost everybody above stated, you can't do 2-2 because of the door anyways. You'd do something like 2-1-1. Doing 3-1 is definitely the most efficient way, it even gives you the opportunity to blow literally every single one of your defensive CDs (HG included for PLD) during that first pull since the next one is just one single group and doesn't require much mitigation/healing.

If we could pull the 4 packs at once we'd definitely be doing it. Things like that happened in ARR back when dungeons were'nt all so formulaic and had less walls. Dungeons used to be so much more fun back then... Still easy, but more entertaining.