Black Mage Sanctuary - A Guide to DPS

[FunkyBunch]

You should never force Thunder, unless you can multidot with the procs -- using TC too often on the same target leads to DPS loss because of clipping the dot and you have to be more careful with your timers. During ice would be ideal, but it's rarely possible, so nine seconds or less on the previous TC dot is when you can apply a new one. The lower the better.

This is incorrect. The math used for that doesn't include the extra cast time of an F4. If you have 2 TC procs you are doing 780 potency in 2 GCD + DOT potency. vs 508 potency for a Fire 4 Cast.
And 2 GCD is less than the cast time of Fire 4. In short take TC procs whenever you can. Multiple is always better. 2 procs is worth losing an F4 for.