You have to be careful. First, four backups (including the default backup) is a bit of overkill. Plus ransomware loves shared folders. You may come in with every backup encrypted.
You should be able to back one up to a USB external drive or online. If you back up to a USB drive and remove it, it is air-gapped and golden. Especially if you rotate it and take it hope.
Remember, the most important backup is the backup of the whole computer nightly.
