Indeed. I had RSI issues very early in my career, and the standard advice by ergonomists was "Use both hands when doing any multi-key sequence". If you're doing Ctrl-C, use the right Ctrl button, and so on.

I think I've just been lucky that I never had issues with that.

For C-x C-s specifically, my hand hardly moves and definitely does not twist, it's very natural for me to type.