One other question that I came across while setting this up is about using corruption in the rotation. A while back I solo'ed a warlock from 1-55 as affliction spec, using CoA/corruption (talented at the time)/Immolate the drain life.

What is the reason for leaving out corruption on this /click sequence? Is it simply the fact that it is shadow damage in a fire focused spec, as Khatovar pointed to in her earlier post? Or does it actually take more time out of the rotation than it offers in dps?

If there is more theory behind it than this please