Judging pull sizes

[Morrigu]

Being that big pulls didn't really become the thing until towards the end of Heavensward, you really need to pull what you can handle.
Heavensward mind set of big pulls really needs to go away. A lot of the aoes that were once a staple in big pulls have been nerf'd via dmg reduction or cost mp/tp cost increases. I personally have found that the 1-2 group pull runs are faster, smoother and less stressful on both me (as a tank and as a healer).
Understanding what a mob can do to you as a tank is also very important, debuffs and other attacks can wipe you really quick. I few examples would be the bird pack in Bardam's Mettle right after the 1st boss, the zu in that pack can hit you for 23k mitigated. As well as Kugane Castle with the summoner pulling in more mobs that would you really need to fight.

A lot of tanks I see in Stormblood have never played healer so they don't understand the stress and annoyance of some of the bigger pulls.

Also avoid bigger pulls in the lower dungeon. Not much point to doing this with the lack of any real aoes anyways.