BLM is ultimately a situational class when you need to keep focus on your balances while watching where your standing and what procs. Knowing how much fuel is left in the tank for the switch is key as well as knowing when to switch from astral to umbral. In an optimal setting you can always bleed your mana low on fires but if your moving out of an AoE and moving back in you need to be ready to cast blizzard III just to keep the tempo alive, regardless of mana position. That and I don't bother with Thunder II ever since that's an extra button on my hot at (ps4 controller) that I don't need. Thunder III is just fine. <---that's just MY preference.