Alert Timeout?

Hello

I have attack alerts that are successfully being sent to a Slack channel of mine.

Under the Attack Alerts and Portal group, there are 3 definitions:

Priority:
Send Attack Alerts to:
Alert Timeout:

I understand the first two. But can someone help explain what the Alert Timeout setting is? I have it default at 5 minutes but without knowing exactly what this does, I am not sure if I should lower or increase the time.

Thanks!