Hi @AlexBravo , thanks for taking a look, and for replying.
The twiddling hand.
There's no need to physically rotate the hand, as long as in your head the index finger maps to the left character.
I like to visualize chords.
I find my fingers respond well to a graphic representation.
The tradition of presenting mappings with graphics suggests this works for others too.
0MRL provides a compact representation for every chord, but the encoding of finger positions is indirect and confusing.
The best you can do is to associate R with the near (palm) side and L with the far side, but this is not universal, right twiddlers need to do the opposite.
4finger provides a universal graphic encoding.
On the down side, the palm up position implied for the left twiddling majority is less natural than palm down, but that's dictated by the way the digits are ordered in 0MRL.
We are in agreement here.
Conceptual groups are a very minor mnemonic aide and preclude higher priority chord shaping imperatives.
Operational groups are a different matter.
Low finger-count chords are fast but rare.
When a group of keystrokes are commonly used together, one or two fingers can be glued (held) down and no longer contribute to the chord time.
The remaining fingers are effectively doing low finger-count chords.
This works particularly well when the glued fingers are less agile.
Examples from thumbless are typing a string of digits, or moving the cursor and viewport around.
Gluing is just how it feels to me when I hold down one or two fingers and complete multiple chord with one or two other fingers.
The Twiddler is also glued more firmly to my palm.