I’m still new to tanking duties. 60 Paladin, 50 war and 70 gnb. However, I try to wall to wall with a few exceptions. I only half pull the first pull in dungeons below 45 anymore just to gauge the healer a bit. You tend to wipe if you don’t. Tanks don’t have much of a self sustain kit below 50 so it is just wise. Arboretum Hard shouldn’t have been one of those cases. As dps, I see single pullers all the time in low roulettes. I just grin and bear it. No big deal and they usually speed up eventually.
A lot of tanks in low level roulettes were obviously from WoW and they tend to do the single pack method as that is how the game was designed.