This box can be checked if the recurring task is frequency defined.
If it is checked, a single request is launched every day in order to execute the requested process, and as soon as the process is completed, the task is put on hold for the number of minutes defined by the frequency, then the execution is resumed until the end time is exceeded. The request is then displayed in the In process report for the whole execution interval.
This ensures that the request is always stored in the memory once it will have been launched, which can be detrimental to other tasks if the maximum number of tasks launched simultaneously has been reached.