What does ring buffer do if "create new" options aren't specified?

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In the 2.6.2 version of Wireshark (and I think recent versions, too), the Output configuration includes two check boxes, one for "Create a new file automatically after..." and one for "Use ring buffer with X files."

If I enable the "ring buffer" option with 3 files, for example, but never check the "Create a new file" option, is the ring buffer actually used? I tried running a capture for a few minutes, but never saw a new file created. Is there default criteria that the "ring buffer" option uses to spread the data across multiple files?