It may have some scientific explanations, if we look a bit more about what's happening in the brain.
HS : you can imagine three separate blocks in your brain, one for LH, one for RH, and one for coordination.
HT : you can imagine that these three aspects are scattered somewhere, and finally you don't know exactly what's happening.
I'm not sure if you see what I mean (I'm not sure myself), but let's say it seems natural to separate big problems in little simple problems.