Well, I can't speak to SMN point of view, but as a tank I can tell you that there should rarely if ever be agro problems.

It's all about context:
Is the tank far less geared than you?
Is the tank busy trying to agro 2 or more enemies at once?
Is the tank dealing with mechanics that force them to do less than max agro? (ex. moving around, at range instead of melee, cursed voice in t7, etc)

If nothing special is going on and you're still getting agro, then it's probably the tank that's bad.

For instance, as a Warrior I'll lead with Tomahawk, Unchained/Berserk, the high agro combo attacks with Brutal Swing thrown in. That locks agro on tank very easily. If however, Unchained/Berserk were on cooldown and Warrior tried to lead with Storm's Eye combo (higher dmg, less agro), then agro loss would be much more likely.


As PLD I would lead with Fight or Flight, Shield Lob, and RoH combo with Circle of Scorn and Spirits Within woven in. Again, very high agro right at the start. Harder to mess up agro on a PLD than WAR.

Bottom line for the SMN: watch context. If tank is doing other stuff, go easy. But in normal circumstances you should be able to throw absolutely everything at enemies right from the start. If it continues being a problem, your tank needs to improve or be replaced.