Arguing the most efficient use of LB is a different matter entirely but thank you for explaining the numbers to me as I always did wonder where exactly the pay-off leaned in favour of caster, beyond (obviously) very large pulls.
What I was referring to by "window" was the minimum time you should allow if your goal is to have a full LB bar by the final boss. If you believe that's inefficient then that's perfectly fine and I'll take your word on it for my own runs in the future, but the OP came across as hesitant and concerned about the opinions of their fellow party members as a result of using their LB at an 'undesirable' time and - regardless of whether its ideal or not - the standard is to LB the final boss, so having a full bar for that will, at the very least, avoid any potential grumblings from any disgruntled DPS in the party.
For the assertive type, its simple enough to just explain your reasoning should you be questioned, but being shy about things like that myself, I know I would at the very least hesitate to break from the norm - I figured the OP might be a little similar.
You're not wrong about the final boss often dying/reaching the point where a single bar will suffice before the second bar can fully charge and - prior to your suggestion - I would have said that's simply another matter to consider if you're familiar with the run, albeit I believe it varies from dungeon to dungeon and, naturally, party to party. Though with all that said, I am by no means an avid dungeon'er these days, so I am not the most experienced with 4.0 dungeon content and I'll leave it up to the rest of you as to how those ones tend to go.
