When to Use Numbering

[Maero]

Depends on the group but myself as a dps i would say i much prefer if the tank numbers targets. Some dps i will admit are tunnel visioned and do not pay attention to which target tank is focused on.
Too bad you are not on Leviathan, our FC would of helped you ought

[Ravenspire]

I find it very useful if the tank numbers the targets, when I'm Playing DPS, even in the lower level dungeons. That way I have no guesswork, I can follow along with out worrying about messing up the tempo of the fight.