The script could check the day of the week for the current date and exit without doing anything when it's the week end.
In the FMS Admin console, when setting up the schedule to run the script, if you choose "Weekly" for the time frame it will give you the option of which days of the week to run the script on. Despite the "Weekly" name you can also choose to run the script 'once a day', etc. Perhaps seems a bit counter-intuitive, huh? :)