You can setup the alerts so that you are alerted to events that occur in the premarket time frame. That will maximize the chances that the pricing action happens largely intraday.

For events that occur in the evening, after market close at 4pm ET, investors have a longer time to hear about the event and react to it from 4pm to 930am the next day. As a result, there is often a "mean reversion," at the opening bell where investors take profits from the overnight action (if bullish event) or buy the dip (for bearish events).

For events that take place premarket in the am hours ET, there is less time for investors to hear about the news and react. And large, professional investors rarely trade before the market opens due to a number of reasons including low volume, work schedules, commuting schedules, etc.

You can set the alerts for any scenario to identify when the events occur and receive alerts for events that only occur during your specific time window.

After setting up a custom alert using the big green create alerts button, visit the My Alerts section of the Dashboard and click the bell icon. This opens the alert settings where you can adjust when to be alerted based on the time of the events.

If you set the frequency to hourly, from hours 5 to 10, you will only be alerted to events that happen between 5am and 10am ET. 

This enables more intraday price action for scenarios where companies are reporting premarket. These events are typically return of capital events (dividends, buybacks). For other scenarios like the activist investor scenario and layoffs, they can occur through the day but you can also limit alerts depending on the time of the events.

Please note that the 1D event impact calculation is based on the closing price prior to the event to the closing price after the event. Often, the maximize returns for an event occurs mid-day, at the high point of the share price and not at the close. Often there is more alpha (returns) in the event trades then is shown by the 1D impact metric.