Reading your post I remembered something about an experiment I heard a guy related to neuroscience talk about recently.
It said that two groups of people had been trained. In one they played the piano and in another they simulated each practice of the melody with their eyes closed.
The second group practiced only on the mental level. According to the study, the members of each group developed similar neural connections. Awesome!!!
Yes. The mental practicing is the same important as with the instrument. Actually, it is all coming first from there. ;)
That is just awesome how our brain works, only if we would be able to use a bit more of it hehe 😄