Cron schedules can be very useful. They look confusing at first, but are really nice to use.
Select cron schedule, select the time range you want to search, and then the cron expression is how often you search.
*/3 * * * *
says you want the search to run every 3 minutes,
*/15 * * * *
says you want the search to run every 15 minutes, and so on.