I see these kinds of benefits in over-learning keyboards as well. The few classes I've taught to children and teenagers, you can see a dramatic difference between the students who are familiar with keyboards and those whose parents--I speculate--don't allow them screen time.

This extends into adulthood. The people I work with who have that well-practiced familiarity with keyboards and keyboard shortcuts--using them as if extensions of themselves--easily adapt to any new software interface. The adults who hunt around the screen with a mouse have a great deal of difficulty with change and are almost helpless when confronted with a new interface--even if the menu items are all in the same places as the last software.

It's a comfort and familiarity with the computer that allows the user to easily adapt to new things. It totally makes sense to me that working with an abacus would have similar benefits for making students comfortable with math.