Quick question about something i noticed on RawrFollow

It depends. Sometimes it favors int for you because of your mana pool compared to the fight length that you have given it. If you pick a longer fight (such as those in Ulduar (5+ minutes, etc)) it will try to make sure that you can last the fight, even with properly timed evocates etc. If you turn on the switch for an innvervate see if that changes it or decrease the fight length.

As I've said before, Arcane is good in Naxx, not so much in Ulduar where arc/fire takes the #1 spot.