If you turn off snapping nudge will automatically move in one millisecond steps, otherwise it will move things based on the current grid divisions. This works fine for selected media but not so much for the play cursor as there is no command action to nudge the play cursor directly. To do that requires a macro to create a range, move the range, and then locate the play cursor to the range.
- Create Range From Cursor (create a range which can be moved)
- Move Range (moves the range forward, or Move Range Back moves backward, left)
- Locate Selection (moves the play cursor to the range start position)
Essentially allowing you to "nudge" the play cursor forward or backward like you would with media clips.