My first instrument was also piano (classical). I never really thought of hand shape while playing chords either, but I understand the parent comment - since yo

My first instrument was also piano (classical). I never really thought of hand shape while playing chords either, but I understand the parent comment - since your hand position does change, it makes the absolute key much more important, and it makes it more difficult to see the relative jumps. I don't think I ever had a good feel for how chords relate to each other before I started playing the accordion recently. On the left hand of an accordion, every chord interval is identical - C major to D major is just two positions away, exactly the same as D major to E major. It's also arranged in the circle of fifths, so any chord progression can be arbitrarily transposed (until you run out of range on the ends) That really helps me feel how chords progress and for the first time I'm feel comfortable playing chords by ear in real-time.