Random observations and anecdotes:
Unlike many people these days, I learned to type on - gasp - typewriters. Classes were on electrics although I often used a manual, too. I learned fairly early on that for long typing jobs, you have to learn good hand position and use the least force that will do the job.
The model M caused me problems but not wrist problems. It caused me problems in my fingers. After a few hours, that kick-back from each "click" adds up.
For some good pictures of good typing, look at old movies that feature professional secretarial pools. Keep an eye on the ladies' posture, hand position, and light touch.
These days I also type with a light touch partly to extend the life of a somewhat expensive keyboard - one that let's me type without rotating my wrists (e.g., the typing position is similar to shaking hands rather than to picking up a pencil).