I hate the idea of Echo Buff. It should be part of some easy server not whole game.

[KitanaiKoneko]

...If this buff can be applied to a character after 3 minutes of combat, whats to stop people from synchronizing their watches and saying "okay 3 minutes are up everyone wipe" and doing this 5 times?...

Because Titan EX takes something like 6-8 minutes to complete, so you would spend twice that building echo buff.
Because Ifrit EX takes something like 6-8 minutes complete, so you would spend twice that building echo buff.
Because ____ takes less than 15 minutes to complete...
I'm sure most people would rather invest their time trying to complete it instead of investing time so that they can invest more time to beat a fight. And all the HP/Damage/Heals in the world wont keep landslide/upheaval from pushing you off the edge.