I'm using Ubuntu 12.04 and at least once a week I get important and recommended updates. These weekly updates are normally between 50-100 Mb, and sometimes they're over 200 Mb.
I haven't installed anything new in a few months, but those large updates keep coming fairly consistently. It's hard to know what I'm actually downloading, but since it's labeled as important and recommended, it's hard to reject it.
My question: when I download that 100 Mb update, does the stuff it replaces get thrown away, or will I just keep accumulating more and more data just by running my system?