Just FYI - in dungeons, 99% the time an LB is better spent on an AoE trash pull; cast by a Ranged DPS or Caster DPS. An LB on a boss doesn't do more than cut a few GCD cycles off the fight, which is unlikely to make any major difference or speed the fight up by more than a few seconds.

An Lb on a trash pack however can clean it up in no time at all; so waiting for the tank to make a huge pull then popping an AoE LB is the absolute best use of it. However I can also understand the DPS' hesitation to use it, because they think they'll get shouted at for showing any initiative which is a shame