I run a squid caching proxy and direct all my (Fedora or RHEL) systems to use it along with a non-mirror list repository that is fairly close to me. I'm not totally sure what your question is though.
If you want to tightly control the packages that get updated then there isn't much to be done other than manually managing your own repo. Although if it is this big of a concern you should probably be running a distribution that is less volatile than Ubuntu. Say RHEL, CentOS, or Debian.
If you want to tightly control the packages that get updated then there isn't much to be done other than manually managing your own repo. Although if it is this big of a concern you should probably be running a distribution that is less volatile than Ubuntu. Say RHEL, CentOS, or Debian.