Both Carbon Copy Cloner and Time Machine serve different purposes, and you should understand the advantages of both to fully take advantage of them. Both can make regularly scheduled backups in the background as an automated or manual process.
CCC can copy the entire drive and make a bootable copy, so when your hard drive fails, you can instantly boot up into the most recent backup copy of your working machine. This helps keep you going in the event of the drive failure, but then you lack that safety net, use sparingly. It requires a hard drive big enough to copy all the data on the source drive.
TM can make snapshots of the entire drive, and periodic snapshots of files at different points in time. If you were working on one particular Word.doc for a project and it got corrupted and you needed to find an older version from last Tuesday, for example. It will fill up whatever drive you have with these periodic snapshots and automatically delete the oldest versions to make room for newer ones. When your hard drive crashes, you have to boot from an emergency boot drive, which has a minimal operating system and perform a rather lengthy restoration from the TM backup. Hopefully your TM hard drive is not that old, because the continuous use of the restoration process itself can send an old drive over the edge and fail during the restoration process, a good reason to have more than one backup.
You can combine a TM and a CCC backup on a large drive, if you partition the drive and have one logical volume for TM, that way it can fill up that partition and leave the CCC volume (which appears like its own drive) for the entire bootable clones. Again, this is a risk that you lose both when that drive fails. Definitely a good idea to have more than one backup drive, and having one TM dedicated drive and one CCC dedicated drive for each machine is one good strategy.
We always try to save a buck, but when a hard drive fails and you lose the only copy of all your personal contacts, emails, tax records, photographs, music, school or work projects, etc, you will know how much that extra backup hard drive was really worth to you.
Plan for your recovery process. When one of your computers has a hard drive failure, what will be your plan to utilize the backups you have made to restore your computer to working condition, or migrate to the new computer. Understand the CCC and TM process for that, and you can appreciate the benefits of having either one to choose from, as opposed to neither.
Good luck!
