The pre- image of each and every row will be recorded in the online redo-logs. This will happen regardless if you commit once, once per row, or every 5000 rows. The same amout of redo will be generated.

Your rollback segments, however, are a different story. With one commit, you will need one large rollback segment. Committing every row you will still need a large rollback segment because Oracle needs a consistent view of the data from the start of the statement until the end. Otherwise, you will get a "snapshot too old" message.