You can also use the Random Alert Intervals switch to randomize the interval between alerts.

The randomly generated interval is always capped by the Maximum and Minimum Interval values.

if You set the Maximum Interval Between Alerts to 1 hour and the Minimum Interval Between Alerts to half hour, the app will schedule alerts at least 30 minutes apart up to 1 hour.

using the Random Alert Sounds switch You can also let the app randomly select alert sounds for each alert.