Depends. When I'm tanking with a new group it usually takes a pull or two to figure out where the dps stands and what they prefer doing (single target or aoe). Tanks should be paying attention to that and adjusting their rotation accordingly. Playing with a smn and blm in the group is generally going to require a different approach compared to a drg and mnk team. A lot of tanks just seem unaware of how smn works and how much aoe threat they can pull, I've been accused a few times of "attacking the wrong" mob as smn, when all I was doing was laying down bane/miasma II.

Try and explain things, hope they listen and if not, quelling strikes can help make the difference.