It varies between dungeons, but for most level 50 and 60 stuff it's usually best to do enormous pulls and caster LB1 them. If you think of the whole dungeon as one big HP bar, a caster LB1 on 10-15 targets does far more damage than a melee LB1/LB2 on bosses.

As for healer LBs, traditionally they're not used outside of 8/24-man content, where the LB3's Raise can sometimes prevent a wipe (certainly more often since 3.4 improved its effects). I definitely see dungeon runs where nobody'll use the LB at all though, in which case your method is definitely better than nothing. You'll probably continue to get a lot of heat for it, though. Many players have very strong opinions regarding LB use, despite the fact that so many melees will waste them on the last few percents of a boss.