I have not seen any information that Oracle is publishing ISO images through ULN every time there is an update. However, if you have question for Oracle Support it's best to ask Oracle Support directly. This is a user forum and some people, including myself do not even have ULN access.
Generally you can configure the software manager (yum) to read from any local media, including mounted volumes via iscsi or nfs. You can also configure a dedicated server to synchronize with the ULN software repository via the Interent and provide a local installation source inside your LAN.
If you are interested in the 2nd option, check http://www.oracle.com/technetwork/articles/servers-storage-admin/yum-repo-setup-1659167.html
This is a quite common situation with many customers. If you have a single machine on the network that has internet access you can create a local ULN mirror with that system. Here's a technical document on how to set this up.