I have lb on common bar.
As a tank I hate typing...
OK lb already. It's like people are afraid to use it.
In dungeon content
Tank and Healer lb is 100% useless
And DPs just speeds up the fight s few seconds so it really doesn't matter much but I feel your pain op

There are a few places signal bar lb saves time on large groups of mobs with aoe lb but for the most part there is no reason not to use it once it hits full bar.