There is a Normal Board for premade runs. I know there is a QB core, but from experience, if I have a premade party, using the Normal Board to skip the boat loading cut-scene on consecutive runs more than makes up the time for the 1 core.
What I often see are folks with 100 luck not using blessing, and not using a badge still spending 65k per run for that extra core. You basically just agreed for me that again doing those 2 things are much more cost effective than buying the fire buff.
Or are you trying to say that 117 luck for at most 20k a raid (if you only run 6 raids a day all of them the meh drop S3s now...) is somehow worse than a guaranteed +1 core? (Because 117 luck should give you on average~1.8 extra cores in a 4 core raid. Course RNG is rng so results will vary ;-)