Well, after much procrastination, we have tried a second application (she got 5 of them off in the first 24 hours from her first application). We have both small and medium ones, and this time they all stayed on. We just had to scruff her for 5 minutes while the glue dried. And now she has the run of the house.
One tip, if you have a cat who is around 9 pounds (which is the cut-off on small cat), I recommend getting small and medium. Some of Daphne's nails are bigger than others. We use a combination.
So far, the leather furniture is safe.