I saw it too. I do the wrist ones. When I first started I could barely use an 8kg for the flip back and forth on left. Now I can do a few using the 16kg. Going backwards was the hardest, of course. I can tell a difference in finger strength when opening stuff where I can just use my fingers and not my whole hand, like before, on some items.
I did find I could not do these more than once or twice per week because I had some cramping during the day. I think since swings works the same area it could over done easily.