You know now that i think about it,mages only need "know creature" to the max.

The others maybe only need it uptil it shows hitpoints of the monster.

The reason being that a mage needs to know the resistances of a monster to fight it easily,while a warroir/rogue in most cases will use their weapon to do so.

Lockpick and Enchant weapon are for me the only 2 that you need to the max for any class.