Alarm on an "old" tag

I wanted an alarm on a tag to go off if the tag’s value hadn’t changed in some amount of time. With some tinkering, I came up with the idea of using an alarm in OnCondition mode with an expression like minutesBetween({[.]MyTag.Timestamp},now())>5.

This nominally seems to work, but everything else I’ve seen about tag alarms implies they are tightly coupled to the concept of changing tag values. Obviously, the now() binding in the expression is also being triggered even without the tag changing value, or this wouldn’t work at all. But I’m worried that I’m breaking some unwritten rule here and going to regret this in the long run.

Is a now() binding in an alarm config expression reliable? How likely is it that this alarm is going to miss events?