1.5 hrs. filling rivets.  I tried the factory approach using my newly made masking tool and it works great!  Especially using epoxy filler instead of Bondo since it lasted for the entire time.  In an hour and a half I was able to do about half the rivets on the top and leading edge of the wing.  I'd say that's easily twice as efficient as my previous painter's tape approach.

I still have to sand them but I think that will be fast (I'll use the masking tool for that too).

NEXT TASKS:

1. Wing tip assembly and light installation.
2. Test fit of aileron and flap, with likely adjustment of the aileron to line up the trailing edges.
3. Fill rivets - Half done already.
4. Rivet the one on the left wing's step rib that needs special handling (waiting to hear back from the factory on what to do with that hole).
5. Finish one of the composite tips of the elevator.
6. Fill rivets of elevator.
7. START ON FUSELAGE!