There are very few times I've found a healer LB useful. The first question I ask is, can I recover this without using the limit break? (Swiftcast rez other healer or a summoner). Then I ask if I can't do that, can I continue to heal the fight through without using the LB (or would we hit an enrage mechanic). If I can't, can the tank survive without heals while the limit break charges and fires / can I get him healed if he's low afterward? Finally after all that I ask myself if we need the LB for a DPS-burn phase, or to survive an incoming attack (killed spiny plume early? tank LB might save you once... same with ultima-4 bomb tank LB helps keep ppl alive through it!)
Because of how long it takes to fire (so no heals going out), and how long people are stuck in place (oops AoE under your feet now)... it is almost always better to restart than to use a healer LB.