This issue has made me leave so many PTs. If you are gonna fight IT they'd better be BARELY IT and all of your melees need to be at the top of the spread. People have the idea that if you have PL you can fight things much higher than yourself and it's not true. There are many things to be factored in.

Your Acc vs the mob's Eva.
Your Atk vs the mob's Def.
Your INT vs the mob's INT.
Your Def vs the mob's Def
Your Eva vs the mobs Acc.
Your MP resources.

If you are fighting IT mobs you will be hitting them far less often, for far less damage and nuking far less hard. Meanwhile, the mob is hitting your tank far more often for far more damage and soaking up your MP much faster.

Essentially it might take you 4-5 minutes to kill one mob and rest your MP back to full. You might make 200 XP because it was IT. Meanwhile another PT is killing lower mobs and absolutely tearing through them. In the same 4-5 minutes they have killed 4 mobs and may not even have to take a prolonged MP break because of how much MP their WHM can conserve.

1x200 = 200
4x100 = 400

In terms of XP/hr it is almost always better to go with lower mobs and tear through them. Sure people will whine that they are not getting the biggest numbers but in reality it is far faster XP. There is a plugin for windower that will let you see your XP/hr calculated as you go. I've seen low level PTs drop from 4-5k/hr to 1-2k/hr because they wantd to move on to the next highest mob. I'm watching the counter tell us that we're making less XP but for someone reason everyone in the PT is saying, "Wow, this XP is much better!!"

In general people are obsessed with big number syndrome. It's the same way for damage. Almost every job (and most notably BLMs) love to see huge numbers. They will blow every ounce of MP to do the biggest damage nuke they can, and then take much damage, soak up the WHMs MP (possibly dying) and slow the PT down as a result. They could've just as easily used small nukes and let the tank have a solid hold on hate throughout the fight and made much more progress.

Granted, sometimes an area can have a lot of competition for pulls, but still a group shouldn't aim specifically at mobs that are way too hard for them.



EDIT: As a note, endgame merit PTs chain low mobs and often are getting less than 100 XP per mob. However, these PTs, killing low mobs for fast, low XP... are getting 15-20k/hr (in a good one).