Backup between X and Y time

I have setup my Readynas to Readynas backup using rsync and it works fine. What I don't understand is the meaning of the backup schedule
"Perform backup every N hours between X (time) and Y (time)"

This to me should mean that in a chosen time period X - Y, the backup should be executed every N hours, but when Y time is reached any running instance should be terminated since it already falls out of the predefined window.

The behavior I actually observe is that the backup runs even past the Y hour when there is more data to backup. Problem is I need to run the backup only at scheduled times, in order to limit traffic on the network during business hours.

Is there a way how to achieve this using the Frontview backup?

If not, could this be added/fixed in a future release?

Thanks