Summary

When our rule is triggered for more than one instance, for example, when we have a rule to identify pages that were created X months ago and weren't updated in Y weeks:

(type = page AND ((created < now("-1M")) AND (lastmodified < now("-1w")))) AND space in ("<SPACEKEY>")

As soon as the rule triggers the notification, it will send a notification for each of the pages.

Suggestion

Instead of multiple notifications, trigger a single notification with the list of items the rule have identified based on it settings - in this case, the list of pages that fall under the query.