Ah, we only need to follow those steps in my previous post one time. Subsequent runs of the same backup task in CCC will be incremental rather than full (so much quicker). But incremental updates will not update the System volume. This means when the next version of macOS is installed, it won't be backed up (i.e. the System folder will not be backed up), but your data will always be backed up.
To make a full backup in the future, it will be necessary to erase the backup disk then follow the two steps in my previous post. That will cause the APFS Replicator to kick in once again.