A question on full backups

I have forced tklbam-backup to make a full backup once per day by editing /etc/tklbam/conf.

I now have 2 full backups and several incremental backups stored on S3 for this machine.

After reading this post:

/forum/support/20110126/few-questions-new-user#comment-6833

I expected the older full to 'roll off' and leave only the most current.

Can you please explain the normal behavior of full backups and whether there is a way to modify this?

Making frequent fulls, as suggested in several posts to keep the 'chain' fairly short, would use a great deal of storage space this way. Plus it seems to me that the older backups no longer serve a purpose once a new full is made.