What are the differences between the "Launch once," "Launch on several days," and "Launch periodically" schedule options in Customer Journey?

These options control when your Customer Journey will check for and add new users from your selected segment. Here is a breakdown of each:

Launch once: The journey runs a single time at the specific date and time you set. It will enroll the entire audience that meets the segment conditions at that exact moment.
Launch on several days: This option allows you to select multiple, specific dates from a calendar. The journey will run on each of the chosen dates, adding users who meet the segment criteria on those days.
Launch periodically: The journey runs at a regular, repeating interval that you define. For example, you can set it to launch every week on Monday at 9:00 AM. At each interval, the system checks for new users who meet the segment criteria and adds them to the journey.