safe rpm repository for DMZ

Hello, I am thinking to create separate rpm repository for DMZ servers that will server proven packages that are not brand new but released for 2 weeks - 1 month. In my opinion that will prevent any undiscovered security problems in rpm packages to be pushed to internet facing servers.
What do you think, it is good idea and how to do it? For example have repo that is not synced for some time and go through list and check if any of included packages does have reported security problem?

Thank you for your reply.
Lubomir