Coordinate with your party about LB use because chances are (making an assumption here) people in your party have already been berated once before for using LB too early or too late or not at all.
I know I have.
"Why did you use LB? Let melee do it!"
"Wow, way to waste the LB"
"Gg [class]"
"Lb on trash lol"
Gets tiresome and dealing with randoms, I'll just take the "normal" strat of using LB on the final boss before they die unless asked otherwise.