When to use tuplet.staff?

[rpatters1]

It is unclear to me when I should choose the tuplet.staff (in a cross-staffing scenario) vs. when to use the event.staff field on events contained within the tuplet. If there is an example, I am not finding it easily. Even if every event is crossed to a different staff, I don't see why I would not specify it in the event.staff field for every event. What value is the tuplet.staff field adding?