My temperatures commonly fluctuate from 75 to 78 degrees, and sometimes even much more extreme. Never an issue. Obviously you don't want your water temp to drop below 72 or above 86, but beyond that I feel like it's being a little dramatic to say it SAVED your tank in this instance. 75 degrees is not radically cold, and any fish or coral we keep could probably handle this shift if it was a gradual as 1-3 hours.
I mean for gosh sakes have you ever felt micro current temperature spikes and dips while swimming / snorkeling / or diving in the actual ocean?