Based on information in other threads I believe Coil is the only content where you actually need accuracy. I've done HM/Ex Primals, Chimera, Hydra all with a minimal amount of accuracy (360 on BLM) and I've never failed to land an attack. For those contents, it's best to gear up on the secondary stats. (crit/det/ss)

For Coil, you need around 430 acc for BLM, 480 for physical DD/SMN (since their pet requires phys acc) for Turn 5. You can probably get by with a little lower for T1-4.