Hi Quentin ,
I'm not too concerned with arguing the case for default key strokes being setup.
So long as it goes into the manual then people can set the keys up if they wish.
I think these functions can be very useful though. When using object navigation to find elements that we know are on the screen somewhere but may not have a clear sense of the object hierarchy it can be a lot easier if time consuming to just scroll through all of the objects.
I have certainly used this on occasion.
I've assigned them to 3 and 9, prev and next respectively.
Very best wishes,