aaburog said:
You don't always *need* what's been touted here, 1 of this, all you can of dps, etc.
But back on the bard issue: you DO sometimes need more. Say if the ae resists are needed on the dps classes underneath the raid mob, and you need more than 1 mana-battery-necro...throw in a bard twisting 2 manasongs and you're unlikely to run out. Or in some fights you need ae resists in 2 different sections that are too far apart for the song of 1 bard to hit. And we all know that bards increase the DPS of only the ONE group they are in with their group-only songs.
This depends entirely on your level of playing. If your tactic consists of throwing an MT/rampage tanks and healers for them plus anything else you can dig up, then yes, you do need more.
If you have any sense of strategy and an ability to determine how to be efficient, you pretty much only need one of most classes. Bards included.
Some classes are excepted, like pure DPS classes or, or excepted to a limited degree, like clerics and your example: Necromancers are not desirable in numbers greater than two assuming you are going for an efficient kill, as opposed to one.
Properly equipped and AAed Warriors, Paladins, Shadowknights, Monks, Beastlords, Druids, Shamans, Enchanters and Bards are not desireable in numbers greater than one on a given raid, if at all. Sometimes you will need two or three actual tanks like on the Guardian, but in most cases, rogues and monks are sufficient if not optimal rampage tanks.
Properly equipped and AAed Necromancers are not desireable in numbers greater than two, arguably three.
Depending on the mob, clerics are desireable in numbers from 3-5 and rarely 6. Any mob is a waste and unnecessary loot dilution.
The minimum amount of rogues and wizards desireable is equal to the amount of DPS needed on top of the other classes to bring the mob down, with a safe margin. They are, effectively, needed in unlimited numbers.
Rangers and Mages make good substitute Rogues and Wizards, respectively.