Pretty much this. If you've played MMOs like WoW before, you'll be familiar with cooldown rotations. Some bosses have abilities that hit like a truck that either greatly benefit from or simply require a cooldown. If you properly rotate abilities such as EfaE, Virus and Sacred Soil, you can greatly decrease the throughput of these attacks. A perfect example in this game is, as stated above, Mountain Buster (aka table flip) or Death Sentence.
Also, a note on Death Sentence. While Death Sentence is counted as magical damage (ie a WHM Virus will not lower its damage), Virus will still help greatly on the auto-attacks and plummets to come, giving you more time to be able to top off the tank through Infirmity.
