As a BLM? Not really as long as the tank is doing their rotation properly it ain't hard for me to target them then their target and start off with Fire 3/Thunder I-III giving them enough time to gain aggro for single or aoe.

If there's a big gap between our ilvls I'd rather just change to another dps job unless the damage is really needed and I just have to try and not pull hate by either doing quelling strikes or gimping my damage by allowing time to pass between casts.