There is also Threshold Alert and Open Reminder [4.0.0.0;5.9.9.9] for cases where using Expire isn’t feasible or practical.
You have to be careful in both approaches with very slow reporting Items (e.g. once or twice a day or less). Both Expire and threashold Alert require an update to the Item to kick off the timers that eventually recognize that the Item has stopped responding. If the Item goes offline and OH is restarted before that can be detected the timer will never go off.
So I created Restart Expire [4.0.0.0;5.9.9.9] which sends an update to all the Items with expire using their restored state at OH startup. This will kick off the timers again. I don’t have the equivalent for Threashold Alert, but it would be as simple as changing one word in the rule to pull the Items with threasholdAlert metadata instead of expire.