In phase 3 it isn't so simple. You need to save orbs for tether breaks, sometimes the tank will need to extend, etc. In my past 3 clears, I've clicked my "save orbs" macro at least 3 times in a row in at least 2 separate batches. Fact is, the tanks need orbs when the main guy has less than 25 seconds on his buff- one Tank can focus the other and thus always have a good reference for when that is; the DPS/healers can at best focus on one tank.