It comes out several times per month, but sometimes there is a glitch that means that the process aborts before completion.
More common is that after completion there is some data corruption found in the data. A year ago, all of the data was supposedly converted to UTF-8, but occasionally an entry in a non-UTF-8 character set is found to have made it back into the data.
Many of the downstream data users only download the RDF once or twice per year, and some are still using copies from 3 or 4 years ago; so whatever the ODP does, it is usually doing it a lot more regularly than is needed by the downstream users. As long as something appears at least every couple of months, most users would never notice. In reality, it usually appears several times each month.
