I've encountered only one group that was specifically wiping at the 3 minute point to fully stack up Echo, solely so that we'd have as much time as possible to attempt the fight with full Echo as possible. It was Titan EX.

Even after two full attempts of doing it this way (meaning, two hours; 30 minutes of wiping and 90 minutes of legitimate tries), we still didn't win doing this.

*shrug* Just goes to show for me how useless the buff is for that particular fight.