The frequency of Enterprise Linux patch cycle

For Linux OS, Oracle provides a channel with suffix "_patch" for package update(E.g el4_u6_x86_64_patch, el5_u4_x86_patch). The _patch channels provide RPMS for only the packages that have changed since the initial release of a particular version (whether an update or a major version). This could be because of security erratas or bugfixes. If multiple releases are created for the same package, due to multiple vulnerabilities found at different times, these channels will always provide the most recent version of such a package.