How to configure retrospect 7.5 to backup daily to multiple external usb hard drives

Hello,  I have a doctors office with a server that houses their entire EMR software & patient data.  We want to know the easiest and most effective way to configure retrospect 7.5 to backup nightly to multiple usb hard drives.  For example, I have a external hard drive for everyday of the week & want to backup every monday to the "Monday" drive.  Is there an easy way to do this & configure it so that after the initial backup it only does the new & changed files?  I have played with retrospect and think I understand how it works, but would like an outside opinion from someone that is doing a similar scenario.  I'm not 100% sure I have it setup correctly.  I get lost when looking at the program though.  I have a backup script for every day of the week, example Monday, Tuesday, etc.  and a destination like Monday-a configured to point to the external media named monday-a.  All of the hard drives take drive letter F: when they get plugged in.
The server is running Windows server 2003 standard with sp2.  Is there an easier way of configuring it?  We get a lot of failures.  Please help.