The Latest Releases section is generally updated with comics that are added to the service weekly.
You can keep an eye on upcoming releases by the month in the Watchtower category — for instance, here’s everything that is coming to DCUI for the rest of September!
Threads like the one linked above are created monthly. You can follow the whats-coming tag to get notified when a new What’s New thread is up for the entire month, and/or the whats-new tag for updates on weekly releases. 