Typing one-handed

is very error-prone. I remember a suggestion that the superior quality of older letters was partly due to having extra time to think every time you re-dipped the quill. We all know there are several biases to the sampling involved in that evaluation, and if the principle is true my output should be of nearly Shakespearean quality for awhile.

Rotator cuffs are amazingly complex machines, but they have several unpleasant failure modes, and I gather they don't heal as well as simpler systems.