Mind Flay: Coitus Interuptus?

Some of the earliest advice I received on dps for my shadow priest recommended I interrupt a mind flay channel when something else became available, especially mind blast and shadow word: death. I think the advice theorized that mind flay is the lowest dps spell a shadow priest can cast, and coupled with the fact that it can’t crit, make it the ugliest brother in the shadow priest arsenal.

But I'm reading more and more shadow priests who channel mind flay through all the way to its end, even if others spells become available.

Most recently, my break/finish mind flay has been situational. I usually let mind flay finish during the early and middle stages of a boss fight. But towards the end, when the boss is nearly dead and some burst damage can help bring it down, I'll break a mind flay to use shadow word: death or mind blast. I also favor using mind flay when a trash mob is nearly dead and I know I won't be able to land a mind blast in time before the mob hits the floor dead.

I plan on doing some additional digging, see if I can find a group consensus on the matter. In the meantime, I'll keep mind flay at the back of the rotation and pull out when the situation calls for it.