Each tank should be aware of how much damage they can endure from trash mobs. it's common sense and respectful to start a pug with reasonable cc. By the 2nd or 3rd trash group you will have an idea of high the dps and whether the healer can cope with less cc.
Its not only about the healer. If the dps is too low and unfocused then that is also a problem. 5 mobs at 10% hp still hit as hard as they do at 100%. Quickly killing one mob is sometimes more effecient than cc. Therefore the need to cc is sometimes determined more by the skill of dps, than the healer or tank.
Its not only about the healer. If the dps is too low and unfocused then that is also a problem. 5 mobs at 10% hp still hit as hard as they do at 100%. Quickly killing one mob is sometimes more effecient than cc. Therefore the need to cc is sometimes determined more by the skill of dps, than the healer or tank.