Disagree. Most hotel front desk systems still run a sweep at 12 or 1am (possibly later, but that's the typical time) which clears out any reservations which were not checked in, even if guaranteed. In such cases you can lose the "guaranteed" room and it gets to be a mess. Calling in advance is very useful in such a scenario.

To the OP, I'll echo the sentiment of others: Never, save for late arrivals.