Automatically split takes into individual files in Final Cut Pro
Select the clip you wish to work on in the browser, then in the top menu bar for FCP, select Mark > DV Start/Stop Detect. This will break the clip up by the start/stop metadata generated when you were shooting.

The options in the user preferences are for timecode breaks that occur during capture.

ps: I don't know when this DV Start/Stop Detect feature was first included, but it was in FCP3 in 2002...