If I'm understanding your question correctly, the only way I can think to do that would be to use an advanced alert and set a delay equal to three polling cycles on the trigger condition tab. For example, if you are configuring an up/down alert and your polling interval is 120 seconds, you would set the "Do not trigger this action until condition exists for more than" field for 6 minutes.
Hope this helps.
Thank you for your answer. I´ll apply this rule in my alerts.