I fyou have seven hard drives, one for each day, simply create a backup to disk folder on each drive named apprpriately (ie: Mon-B2D, Tues-B2D, etc)
Create one job for each day and schedule it to run on ONLY that day. Select the appropriate B2D device for that day's job.
Do this for all seven days.
You should have seven jobs created in Job Monitor, each schedule to run on only one day of the week. Each targets it's own B2D device which is on aseperate drive from the others.