How can I create versions of my backups when I'm not using ZIP compression?
SyncBackSE and SyncBackPro include a versioning feature that will keep previous versions of your backup files. To enable versioning: modify your profile > Expert mode > Versioning settings page. Note that you cannot use versioning if you are doing a backup to a single Zip file.
For SyncBackFree, you could create a profile for each day: First, create your profile and copy it to make two new profiles. Rename these three profiles, e.g. Monday Backup, Wednesday Backup, and Friday Backup. Edit each profile so they point to a different destination, e.g. the Monday one could point to a Monday sub-directory. Then just schedule the Monday Backup to run on a Monday, etc.