You may have noticed that currently only the following option are available to configure the scheduled task: hourly/daily/weekly.
There is no alternative to include a timed interval for each of those selections. For example, if daily is selected, possibility of adding an interval option of every second or third day; If weekly is selected, possibility of adding an interval to send it every 2 weeks. And so on.
This is by design. An enhancement request (TF00654740) has been created detailing the interval feature above.
The product team will evaluate the request and this feature may become available on a future release of the product.
Please refer to this article for updates or contact support referencing the Enhancement Request ID: TF00654740.