We don't have a specific number, but what I've found is the combination of managing "Smart Alerting" and inbox rules help greatly. If you turn ON Smart Alerting, you'll only get 1 alert at the start and no more until you either confirm the incident via the Incident Dashlet for the appropriate System Profile, or after significant time has passed so as to ensure the two incidents are not in fact the same. With Smart Alerting off, you'll get constant emails. If this is the case, you can set up an inbox rule to grab all the alerts for organization. Short version is: No, we don't have the feature to alert a specific number of times.