I resent the idea of an absolute standard of ergonomics or typing technique. I often use my left thumb to key z/x/c/v/b. I often reach with my left index finger to key y/h/b. During certain chords, my hands often cross over the split.

I tried multiple split keyboards over the period of 2 years and never grew out of these habits. I always wished, at the least, that some of the middle keys were duplicated between the two halves.

Eventually I received some permission to accept my personal "kinetic signature" (so to speak). Then the chronic wrist pain that led me to try split keyboards in the first place vanished. So I went back to using a normal tenkeyless. This led me to believe that split keyboards were ideal for some people, but that other people (like myself) are predisposed to a sort of perfectionism that entails physical guarding and chronic pain.

I still wish I had a wireless split keyboard for times when I'm supine and need to type, though.