> have this happen every morning at 5AM by creating a temporary text file containing this line: 0 5 * * * rsync -vax --delete --ignore-errors / /Volumes/Backup/

This leaves you needlessly exposed to this failure mode: Commit some "braino" that wipes out some recent work. Go to bed without noticing the loss. 5am rsync run wipes your backup as well.

The fix is to back up to not just one but to a rotation of images. Use --link-dest to reduce storage overhead to the size of the directory hierarchy only.