It's not too bad because there are multiple reminder alerts on-screen at regular intervals (every 4 hours I guess) and after the final 16-hour limit, it triggers (again after alerting you 30, then 1 minutes beforehand) and the actual process takes 5 minutes.
It can be a major nuisance if you are in the middle of, say, an office VC meeting or a gaming session, but workaround is to simple run the thing manually just before any important session.
It seems there will be firmware update (soon for my model 321UP) to increase the limit from 16 to 24 hours, already released for some other models.
